After picking up a WRT54GS earlier today I've done some preliminary work on a web administration interface written using Lua. I've built a lua package that includes the standard lua interpreter, but I've also written an alternative app to use as an interpreter for Lua CGI scripts that runs setup code (argument parsing etc.) and outputs errors cleanly to the browser. I've also written a simple templating system. You'll find everything here:

http://gir.eclinic.com.au/~lsd/openwrt/ipkg/

Install the lua and foocgi packages first, then grab the tarball. You can extract the tarball to /www if you like, but I've been extracting it to /tmp and running a second web server process to access it:

httpd -p 8080 -d /tmp/lua-web/

All that's there so far is a very basic network status page, and a display of the /etc/hosts file, but I think it should be a solid foundation to work from.