A game system like the battlemod available for invision boards would be cool to have.
That was a time ago the only reason it takes for me long time to switch to vBulletin.
At my old site it was very popular.
Interesting, there used to be a mod called Tk-egg avatar where you could attack an avatar, but making it a member vs member and the attributes of ownership of vbshop objects making you stronger/weaker is very interesting per se!