Since setting up your own forums seems to have become the latest fad on the Internet, here's one VERY good free service. Invisionfree gives free forum hosting with an address of the type:
They provide IPB (Invision Power Board) boards, which seems to be the best right now - Our own dear MSFN runs on IPB too. InvisionFree will take care of the head-ache of migrating to IPB 2.0 when it releases as well. 16 MB of disk space (which you'll take a long time to reach, maybe 500 members at medium activity for 6 months), and no limits on bandwidth. Relish it?