It's a very trivial thing, but some of them are quite outdated. There were a couple empty ones, and a few with a dearth of active members (for example, before I came back this week the two Decamark groups were made up of a grand total of 4 users who hadn't been active in two years).
Again, an extremely trivial topic, and if we don't want to fix what's not broken, that's fine. (Never mind the fact that I've been here for a couple days and here I am suggesting an overhaul of something.) I just feel some simplification and excising could be in order. Maybe combine a few groups and eliminate another few entirely.