Quote Originally Posted by Yamaneko
Simple?: http://www.phpbb.com/

Better, more complicated, but still free?: http://www.invisionboard.com/
Those are both good and great, but that's assuming he already has a host for them with PHP and MySQL included in the package. Though, correct me if I'm wrong, Lycos.co.uk offers that in their free webhosting package, so you could look into that.