What about a bemani board? Bemanistyle.com used to have a nice one, but they're down at the moment (god knows if they'll ever set their full site back up much less their futaba board).
I think it would get some good usage, you could split it up into Popn, IIDX, or whatever, or just keep it together. It'd have to be an imageboard, because bemani discussions would just end up being "omg i just missed AAA on v[a] by (num jgs).
Thanks (b**)b