Just looking around for components for an issue tracking system. One key feature would be that users can setup their own controlled vocabulary for their issues...
Googling around
* First result: other people already have wanted this, but i could not find a premade module that does it
* Second: there is an old issue about this with a fine sketch from moshe
* Third: the og_vocab module does something quite similar imho: a vocabulary for each group.
This module might be a good starting point to start hacking. Right now i'm not enough into drupal to do it but i'll leave this as a note to myself and interested audiences. :-)