I setup Freeradius with a web forntend a few years ago for a public wireless provider - had to do some modifications on the web based stuff to make it do all they needed but you could setup users etc
http://www.freeradius.org/dialupadmin.html should give you some info
Had a server running Radius, a DB server and a webserver for the forntend - using WRT54G's modded with OpenWRT to connect in - worked ok