I haven't been there for ages, but last time I was, it was pretty much punk: Jolly Roger.
It's a St. Pauli (footy) place - so if you're into HSV, better don't go

Just found them on
myspace.Acc. to that site it depends on the dj, what music...
But might still be worth a try, at least you will find lots of punk fans there who might give better advice than I can.
If your German is OK, you can also check the
St. Pauli Klönschnack Forum - if you ask for punk venues there, you'll get tons of answers, there's also an English Forum on those pages, you could ask there.