Can the groups overlap?
Could have a lords group, a ladies, a liege, a donor box, a Dom box, a sub box, a straight box, a gay box, a bi box, a regional box (separated by time zone or country, doesn't matter), a food box, a game box, a snuggle box, a newbie box, a rant box...
I'm just throwing out ideas; I don't step into the SB much so I don't really know how the groups that frequent it would identify.