An FTP server. It wasn't the greatest because we're in Australia so the upper limit was a 15 kb/sec tranfer. But if you're in college or have access to a super fat pipe you can get mb/sec transfer speeds, which means people aren't really cut off. We shut down because our ISP capped uploads to 3 gig a month, and we were putting out more than that - even at the slow speeds.
Another option you could do is host a DirectConnect server.
www.neo-modus.com
Thats pretty good because it's like a personal Kazaa server.