chat and a message board. Not many free forums out there PHPbb can use a system called PHPnuke.
For my site Im using a new system called IPB nuke. Based off PHP nuke but ment for Invisioin Boards if you have access to a old version of IPB 1.2 1.3 you can still use old versions of the script.
I for one am for a chat system but a good chat is hard to come by
IRC (Jave or Application) would be good