Fansub groups sounds like a great thing to document! We've got one page on fansubbing and a few on the history of scanlation, but I don't think we have anything about the groups who do it.

Something like Category:Fansubbers & Scanlators? Is there a specific term for these groups?

We have a comparable category for a different kind of fan group:

http://fanlore.org/wiki/Category:Doujinshi_Circles_%26_Doujinka