Here’s a free “Buy You A Beer” script for phpBB.
This script allows forum members to send each other money
using their PayPal account thru your forum to buy virtual
beer for (and transfer money to) other members.
It can use any currency code that PayPal users and you can
set how much for a jar of beer and how much for a cup. You
can set a beer tax, which goes to administrator. Users are
able to view all account details and transaction history.
http://www.phpbbhacks.com/download/6314
Side note:
If anyone knows of a script like this that can be used with
SMF (Simple Machines Forum) please let me know. I’d love to
be able to add this to my forum 
