Engadget has linked to a story on Wi-Fi Planet about the hackability or the WRT54G. We covered this a while ago, but I went hardcore with mine and did everything with the console and config scripts. This article covers a distribution called DD-WRT that wraps a lot of the more common OpenWrt enhancements up into a nice web app. So you still have a web-configured router, just with more settings available.
If you thought that hacking up your router sounded like a good idea, but too much work, this article is a good read.