<---a open source forum. Just get the package, and install it in your server. Installation is very easy and a good forum too.
But if you are running it on a *free* webspace provider, you may run into lot of database connection problems. Atleast that is what i experienced. You often get errors while accessing forums [due to traffic etc etc] . In that case, you can use this link www.armleg.com
, they provide you free forum ,all setup . Just need to register and you are the admin of that board.