Controversy is great for igniting politics type forums.  It doesn't seem quite right, but if you can argue with yourself (so as not to offend anyone) about some major controversial issues then that should get some reaction.  You could swing by other larger political and debating forums and see what issues are getting people's backs up and then introduce them to your own forum.  Is this a completely new forum?

Largely, it seems the major national issues and even international issues trickle down to the local community level.  For exmaple, although the Iraq war is a national/international issue, you can be sure there are localized reactions to it that would make major points of debate. 

How local are we talking here?  At the state level?  Township level?  Perhaps a trip to the town hall would yield a half dozen good local debating points.  Or looking over the local rag?