I just finished the phpbb3 plugin for Easy Member Pro.
Its available with version 3.0, which is set to release on Jan 16th.
Were currently using it with our forum.
This plugin allows forum members to be created automatically, activated automatically, and assigned proper group permissions. same goes for deletion, and deactivation, and group removal.
Members are auto logged in to the forum when they login to the easy member pro members area.
Group permissions are assigned to membership levels.
You configure which membership levels are related to forum groups.
I think its the best out there, but I created it so ...
Here a link.