Basically the idea is a way to trace who invited a user. So that you can link back the referring user in the tree. (Figure it might also help encourage some responsibility.)

I get the sense that the problem is that groups proliferate but are never active. The problem with that is that it clogs up the directory, so that people who are browsing around the site, looking for activity, see a bunch of inactive, unpopulated groups and figure that the site isn’t very exciting.

Your suggestion for group combination might solve part of the problem. But I think the real answer is to provide the right kinds of filters, and the right default filters, so that people browsing around the site are more likely to see the active groups than the dead groups. That’s not to say that you should hide dead groups altogether (though a plugin like Mark’s would effectively do that, and I can see an argument for doing so on a provisional basis), but that you should make them not quite as easy to find as the active groups.

Or, let junk groups proliferate in a wide, open breeding ground (why stifle enthusiasm?), but create a plugin that allows groups to merge easily to form stronger joint entities. The plugin could include some kind of game-like diplomatic functionality where one group makes a sort of overture/proposal to merge with another group, which the second group has to accept in order for the merge to take place.

I’ll fix this on the next rev of the plugin. Thanks for the feedback.

If you mark a user as a spammer, they are still visible when you send group invites.