OpenWrt
If you also are an unhappy owner of a Linksys WAG54G router, you might want to try this. They say it’s compatible, but without a JTAG cable I don’t really dare to try.
OpenWrt is a Linux distribution for wireless routers. Instead of trying to cram every possible feature into one firmware, OpenWrt provides only a minimal firmware with support for add-on packages. For users this means the ability to custom tune features, removing unwanted packages to make room for other packages and for developers this means being able to focus on packages without having to test and release an entire firmware