Carsten of Langå, Denmark, a long time & valued YaBB community member,  and author of many of YaBB's best mods... has just released Quiz For YaBB 2.1 mod on BoardMod's BETA Mods for YaBB 2/2.1 board.  This mod will allow to create a quiz system with your Y2.1 forum.

Here is Carsten's remarks in the post:

I've more or less rewritten the Quiz mod originally by Pyrrhon to make it work with YaBB 2.1
 
Also added some new functionallity and shaped up the layout.
 
File structure is the same as in the original mod to let you reuse existing data.