Tomato is a small, lean and simple replacement firmware for Linksys' WRT54G/GL/GS and Buffalo WHR-G54S/WHR-HP-G54 routers. It features a new easy to use GUI, a new bandwidth usage monitor, more advanced QOS and access restrictions, enables new wireless features such as WDS and wireless client modes, raises the limits on maximum connections for P2P, allows you to run your custom scripts or telnet/ssh in and do all sorts of things like re-program the SES/AOSS button, adds wireless site survey to see your wifi neighbors, and more.

http://www.polarcloud.com/tomato/