I have one of these:
http://www.nseries.com/n800
it has been replaced by one of these:
http://www.nseries.com/index.html#l=products,n810
The replacement has a built-in 12 channel, WAAS compensated really hot
GPS, but my GPS is one of these:
http://europe.nokia.com/link?cid=EDITORIAL_173733
which I think is better because I can mount this GPS receiver anyplace
out of the weather with full view of the sky, and it doesn't matter
where I put the tablet as long as it's in Bluetooth range, 10 meters, I
get perfect GPS data, certainly anywhere on a boat. It's so accurate,
it will place your car in its parking space at the mall on the mapping
software further down this message.

All of these are lithium-ion cellphone battery powered, but their little
chargers plug right into 12V and you can buy more for $10 at any
Walmart, standard Nokia cellphone AC or DC power supplies. Just plug
them into the boat's 12V and they'll run forever, or you can run the
tablet for hours and hours on its internal, changeable battery before
plugging it in to recharge.

These tablets are all Linux powered by a mini Debian Linux called Maemo
Linux. They are all open source and Nokia provides whole new updated
operating systems free to their customers, seemingly forever. The N800
is the same computer as the N810 but without the keyboard and they use
the same new OS2008 Diablo version of Maemo Linux. Until now, updating
meant plugging them into a Windows PC and flashing the EEPROM with a
little application from Windows. Diablo updates itself, even to a new
OS!

What good is it? Where's the software to make it do useful things?

Nokia handed these to the hackers and said, virtually, "You boys figure
out what it will do and write free software to make it happen under open
source. Here's a web server you can use so our customers can download
it free and get updates and new stuff." http://www.maemo.org/ was
born.

The community runs Maemo.org. We even have elections like any club if
you wish to get involved. If you're not a programmer, that's fine. I'm
not, just a user sucking at the maemo tit, so to speak. If you'd like
to see a new feature or have an idea for something totally new, the
geniuses in the "garage" (garage.maemo.org) will actually listen and if
they like it, make it happen! That's how all this stuff came to be.

To look at all the software available for an N800/N810 tablet at once,
use:
http://maemo.org/downloads/updated/OS2008/300/
It will take a while to load as it loads every app's header in the
server in the order they were last updated. It's the only way I know of
to look them all over in one place. Normally we use:
http://maemo.org/downloads/OS2008/
which has them sorted out into categories I find hard to use,
personally. GPS apps are under travel, for instance. I'll show you
them in a minute.

All applications are so easy to install. Notice the GREEN ARROW? You
go to the webpage with the tablet's own Firefox browser, click on the
green arrow, it sends an instructional "install" file the tablet
recognizes and boots the Application Manager. A few windows popup
telling you Nokia didn't write this software and they are not to blame
for anything the hackers at Maemo write. (Not to worry, it's fine.)
Another popup window asks if you really want to install this. You click
OK and it installs automatically...including all the ancillary library
Linux files necessary to make the software function, if not already
installed. IT'S EASIER THAN WINDOWS!

For the boat, there are some really neat applications, some not even
related to GPS/navigation topics. You'll see Vagalume, for instance:
http://maemo.org/downloads/product/OS2008/vagalume/
which connects your tablet either over its Bluetooth tethering to your
cellular phone (it's not a cellphone which is why it has all this neat
software without the sellphone company blocking it)...or...connected to
any wifi system it can find. Tethered to a bluetooth DUN enabled
cellphone, it will have internet access as far away from the dock as you
can use the cellphone...2-3 miles at sea around here on Alltel and all
up and down the ICW, rivers, lakes and harbors. At the wifi marina, of
course, it runs much faster on wifi than a cellular phone "broadband"
can go. Connected to Last.fm with Vagalume, it will play music YOU like
much better than Sirius/XM for the price of internet service, however
you get it.

There are lots of other multimedia apps to play movies, music, videos,
etc. If you install KMplayer:
http://maemo.org/downloads/product/OS2008/kmplayer/
which is a front end for mplayer, the finest media player for Linux:
http://maemo.org/downloads/product/OS2008/mplayer/
then you can install the World TV 99 playlist app that will allow you to
play some really great color television stations already pre-programmed
into World TV 99:
http://maemo.org/downloads/product/OS2008/worldtv99/
Because World TV 99 is treated like an app, it automatically updates the
list as the geniuses at Maemo find more TV stations unguarded by
encryption. World news comes from CTV Canada and France 24 (in English)
as if you had cable TV! Of course, Corporate America can't watch TV via
internet because it has no box office to deposit money into.

The tablet will play all the MP3 files, DivX movies from Usenet, Real
Player video and audio....just like your home computer does. A standard
stereo phone plug plugs into the boat's stereo power amp like Sirius/XM
or the stupid iPod does to play throughout the boat....without paying
Apple, of course. No itunes is necessary.

Any computer files in the N800 are stored on TWO standard SDHC memory
cards of any size made, now up to 32GB each. I have two 16GB SDHC Class
6 cards from buy.com I paid $54 each for, a massive storage space for
movies, music, Google/Virtual Earth maps, satellite picture tiles,
movies and pictures from the N800's own little webcam that pops out the
end, if you like. It's not a good camera. It's made for internet
webcam, not high quality pictures. The various media players will
locate all your movies/music/media files in any directory on any card
for you. it's really easy.

Ok, so it's a TV, movie, music, video player and it will play YouTube
with MyTube app for free:
http://maemo.org/downloads/product/OS2008/mytube/

It also does COMMUNICATIONS via Skype, Gizmo, Fring and a bunch of video
and audio VoIP comm programs! Too many for here.....(c; Great boat
phone over wifi!

So what? What about the GPS applications?!

When I bought my GPS, I bought it as a "Navigation Kit" bundled with the
commercial software called Navicore, which is now part of Wayfinder.
http://www.linuxdevices.com/articles/AT1980399426.html
The kit contains the software you don't need, and may not want, the all-
important suction cup N800 mounting bracket you do need so you can
securely mount the tablet WHICH IS NOT WATERPROOF IN ANY WAY to anything
the suction cup can stick to....and stick hard it does! The mount is
really nice and the tablet just slides right into it from either side.
The GPS and an extra 12V power cable to charge both the GPS and tablet,
as they take the same plug, is included. You may want to find the
mounting bracket separately from what I did and buy the GPS/cord for
$100 from many internet vendors....saving about $70 w/o the software.
The new operating system INCLUDES real Wayfinder and the maps for your
hemisphere's roadways, the whole USA, but it's a DEMO that only runs for
a certain period before it expects to be paid for. Wayfinder is really
nice commercial, talk-to-me-and-tell-me-how-to-get-there, full-fledge
CAR navigation, just like a $500 Garmin that only does this and nothing
else.

Ok, but you said for the BOAT!........

Up until very recently, there was no way to put a marine chart into the
tablet. That has all changed......

Originally, the Maemo geniuses hated Wayfinder/Navicore and decided to
do better. The result is Maemo Mapper:
http://maemo.org/downloads/product/OS2008/maemo-mapper/
Maemo Mapper can use any standardized map tiling server to, on-the-fly,
download and display maps from many sources like Google Maps/Earth,
Virtual Earth street/satellite/hybrid, Yahoo maps/satellite, Open Street
maps.....and now, for your airplane, Runwayfinder.com's aviation charts
for the whole USA/Canada! But, to this date, there are no marine
charts.

This is not bad, however, especially if you are an ICW navigator or any
river, lake, harbor!

Boot up Google Earth on your PC. Zoom in on your harbor or anywhere on
the ICW you like. Zoom in so you can see the boats that were running
when they took the latest satellite photo. Now, imagine if I could put
YOUR BOAT, within about 3 feet, on THAT photo! That's exactly what
Maemo Mapper will do for your boat in your cockpit or nav station with
this little GPS receiver over your cellular phone internet
linking.....on the fly...or...from previously-stored photo tiles you can
download before you go and use it completely offline.

AS you cruise down any waterway, charted or not, in unfamiliar
territory, you could be watching your position plotted on a REAL
satellite photo of exactly where you are on the waterway. You can see
what's up ahead for a thousand miles in any direction.

Would that be useful? It works great! The satellite photo shows you
details that old chart plug they want too much money to update for the
old Garmin never shows. It'll put you right in your slip, on your side
of the fingerpier, right on that picture...it's THAT close!

Of course, this is NOT a realtime satellite photo, it's a few months
old. Google is updating its satellite photo database with a brand new
satellite they had to get the military's permission to use! Those
photos will work on Maemo Mapper as soon as they come on the net.

ALL FOR FREE..............as in Beer!

Now comes the reason I decided to post this, now..........it gets
better!

Some Maemo geniuses are also hikers and use their tablets off the beaten
paths with maps from odd places that have no tiles. they wanted to
track their progress through the forest and mountains on path maps
Google earth just can't show in the canopy of trees and dense jungle.

....so, back to the programmers....and "Hike", a brand new app, is the
results.

What you do with Hike is to create your OWN map tiles with any jpg
digital camera! You take a PICTURE of any map, aerial photo, MARINE
PAPER CHART, etc.....get my drift? and store it on the tablet's easy-to-
load memory cards. You point HIKE to the PICTURE of the MARINE CHART!
Hike displays this PICTURE, any number of pictures limited only by your
capacity to store pictures on huge memory cards, to you.

Exactly like calibrating the B&G Yeoman paper chart plotter boaters have
been using for years, at great expense I might add as we have one on
Lionheart I adapted to the chart table itself:
http://www.smgeurope.com/product_display.cfm?id=1816
http://www.yachtbits.com/yeoman/navigator_pro.php
what you do is to click on the picture with the tablet's stylus and feed
HIKE the lat/long of that point for at least 2 points, but 3 is better.
Yeomans require 3 points and Maptech Charts are prestored and have
preprinted calibration points for Yeoman to reference making it easier.

HIKE will store these lat/long calibration points with the picture on
your memory cards, forever. Unlike Yeoman that must be calibrated every
time you change paper charts, HIKE pictures will stay calibrated for
life.

To use this on the boat, you simply tape your marine charts to the wall
and take your best pictures of them....in pieces would be best to make
resolution even better on HIKE. Put the pictures of the charts on the
memory card for the tablet. Run HIKE and feed it 3 calibration points
on each of the pictures AND CREATE YOUR OWN ELECTRONIC CHARTING FOR
FREE! No hundred dollar bills need change hands for little rom plugs
you're stuck with unless you feed them more money later to upgrade. If
a new chart comes out, beg, borrow or steal it for a couple of hours and
take a new picture of the new chart. Calibrate the new chart with HIKE
and delete the obsolete picture so you don't use the wrong one....

VOILA! LOW COST MARINE CHARTING EVERY BOATER IS LOOKING FOR....

Got a lake fishing chart or tournament fishing map noone else has a
chartplotter for? HIKE can turn ANY kind of map that's reasonably
accurate into a REALTIME CHART PLOTTER with your boat accurately
depicted upon it....on that lake.

How cool that is!....(c;

Did I mention after you buy the tablet and GPS all this is virtually
FREE?!

Well, I'm gonna catch hell that this is long but so be it. I thought
you guys would like to see what I found and am using....

I made a vertical mount over my table the camera sits in to take the
SAME SCALE pictures of ALL the charts in the book. This way, they all
work the same. The tracking is as good as you can calibrate the picture
with. I made full-sized, pictures of large areas then closer up
pictures of small areas where you need to see more detail like a closeup
near the home marina. Switching pictures is instantaneous. It takes
HIKe 1 second to wait for the GPS to send it a fix to put you on the new
picture, more or less detailed...in realtime.

I even have the walking tour map of the Charleston Historic District
showing all the historic homes/landmarks/etc. on it. HIKE makes a great
tourguide with the little GPS puck stuck in your watch pocket to find
your position....(c;

You can even run HIKE and MAEMO MAPPER simultaneously and switch between
them!

There are hundreds of videos on YouTube and the user community uses:
http://www.internettablettalk.com/forum as a help community project
to help you fix any problems.

The guy who runs internettablettalk just started a newbie tablet school
website that migrated from another user self-help project, too:
http://www.tabletscene.com/

Every time a new toy is released by the geniuses in the garage, it shows
up on:
http://maemo.org/news/
They're really nice and don't bite, no matter what you've heard about
programmers and coders.....(c;

WARNING - NEVER ALLOW PHYSICISTS TO GET CLOSE TO VIDEO GAMES!
Numpty Physics is the results, a user-game-repository, gravity-based
physics game that will ruin your relationship with other humans for
hours, even DAYS! You can even make your own puzzles and UPLOAD them to
confound those *******s whos puzzles confounded YOU!.....(c;
http://maemo.org/downloads/product/O...numptyphysics/
http://www.youtube.com/watch?v=iCO4eXUJh-I

Oh, no! They've ported it to WINDOWS! The whole world is in danger!
RUN FOR YOUR LIVES!!
http://thpinfo.com/2008/numptyphysics/

I'm told this app is banned at Nokia so some work can get done....(c;
I know they LOVE it at parties.......(c;