Members Hack

I've seen once a board with a cool member area but i don't know wha board.
if you click on the member area
normal you get a whole list with members who is registerd from a to z
but this one has catogories
example:
Members who just have been register where in a catogorie
and the members form 20 till 50 post have a special catogorie with a special Name and Admins etc etc
i made a little draw

Realy nobody that can help me??