The OpenWRT project is awesome. They build custom firmware images for wireless routers that turn those routers into minimal, but functional, computers. We use OpenWRT on some of our wireless routers (the ones that don't have a hard disk in them).
FreeSA piggy-backs on the work done by OpenWRT. The core difference is that the goal with OpenWRT is to use a cross-toolchain to build a new replacement firmware image that resides in the flash memory of a wireless device, while the goal with FreeSA is to use a cross-toolchain to bootstrap an entire operating system installation, including development tools, natively hosted on the target device. (Of course, that requires a target device with several gigabytes of storage -- ideally, a hard drive.)
Check them out! Send them hardware! (We donated a WL-700gE.) Send them cookies! http://www.openwrt.org/ is the place.