I stumbled upon a pretty cool thing the other day.

My wireless router is in the front upstairs corner of my house, and
while it has served me well over the past few years, I recently built
a shop in the opposite corner of my backyard. The wireless network
just wouldn't reach that far.

I upgraded the router to a D-link Extreme N, but that only helped a
little. I was getting ready to think about external antennas or
repeaters, and found the web page for dd-wrt.com It's a web page for
open source software written to run on certain models of wireless
routers that adds (and uncovers) lots of settings and capabilities.

In short, I just got finished loading new code into a new Linksys
WRT54GL router, and then setting it up to be a wireless repeater. It
cost about half of what a decent repeater would, and took about 30
minutes of reading and 20 minutes or so of uploading, resetting, and
configuring to get it working. It's now sitting on a shelf in the
back corner of the house, and it's giving me about a 90% signal down
in the shop. Plus, I retained full WPA security both in the link to
the main router and in the repeated link to the shop. It just shows
up as a new SSID with a different IP address range. Pretty slick.