I am thinking, each group should have something like "Group points" or something, they could get them for activity, or usefulness, or the Mods/Admins could give them for something...
Well, the groups should have some point system, and they could buy group stuff for the points, the group points could be also added to the star calculation formula for the group members.
Guilds could buy their own badges for the points, like suggested , but not only for underground groups...
And I'm sure that you could come up with more things to buy for the group points. I hope this gets accepted. Would be cool.
Sorry, I'm not German. Nicht Deutch.