Yes, but was using openwrt, I once built a captive portal running on a freeradius backend with it.
http://openwrt.org/
If you're a GUI guy, I would suggest you use a firmware by Sveasoft instead.
http://www.sveasoft.com/
__________________
A girl once told me "Give me 8 inches and make it HURT".
So, I fucked her twice and hit her with a brick.