My group's cosplaying Juuni Kokki, which I daresay counts as obscure. Youko, Kyou-ou, Kyouki, and myself as Risai -- I think I win as most minor character of the bunch, though if we're talking the anime, not by too much.
Air Gear's getting pretty big, but I'm working on Nue from it, who is at least comparatively obscure. That's gotta count for something.
I think my most obscure existing cosplay is Okita from Peacemaker, which is only recognisable as what it is due to the Saizo I tend to keep on my head. Got recognised an awful lot at Fanime this year, though, so go figure. :3