Does UBB have any add ons to allow a forum currency system? Where members earn points/cash for different things like posting or being active daily etc.
POST COUNT is the classic currency.
UBBT can automatically add users to different groups (access levels) based on the user's post counts.
Some users view the post counter on a member profile to judge how active that member is. its the easiest and most cross-forum form of "forum currency" there is. This combined with the member's join-date could give a good idea of how useful a user it in building that community.