Our standard recommendation is the linksys WRT54GL. Make sure to get the L version. It uses the old (good) firmware instead of the VxWorks junk, has more memory, and is made with the intention of allowing you to flash it with custom firmware such as DD-WRT. It's usually not availalbe in brick and mortar stores.
http://www.newegg.com/Product/Produc...82E16833124190