I recently bought a Linksys WRT54G wifi router and I am so darned happy to discover that it can be flashed and modded!
Here are a few of the cooler ones I’ve found:
A Wikipedia entry with links for firmware upgrades and what the different hardware revisions are. The new firmware loads are cool, lets you use RADIUS and loads of other stuff.
This one is sweet, how to add an SD card reader to a WRT54G
This project is for people who would like to add a little storage to their Linksys WRT54G router besides the builtin 4MB flash ram. What we will do is connect an SD card reader to some of the GPIO pins of the CPU found inside the Linksys and with the help of a little driver we can use as a block device from Linux. This means that if you compile your kernel for the Linksys with e.g. support for MSDOS partitions and VFAT you will be able to mount, read, write, partition and so on your normal SD cards. The speed obtainable for reading and writing seems to be about 200 KB/s.
Some more information on the GPIO ports.
And if all that wasn’t enough, you can even make a robot out of it
[inspired by HackerMonkey]