Does anyone know a good place to look for router firmware?

I know there is Linux router firmware for the WRT54G but I was wondering if there are other types and brands which can be provided with Linux?

I'l looking for cheap routers.. so Cisco is already out of the question.

The idea is to buy a router and provide it with Linux so I have full control. Like that I hope to create a cheap version of a managed router. I do not want to set a complete computer up to provide me this routing and firewall functionality..to reduce power costs.

Thanks for any advice!