I've got a set of ATH-ANC9s and as a programmer I work in an extremely noisy environment (next to the phones); by themselves they do little to drop the noise, but add some music and magic happens.

EDIT: I experimented with the (almost universally approved of) ATH-M50Xs but found I had to use a much louder volume to cancel out the noise, which causing ringing, so using NC is pretty much saving my hearing. Not sure how I could work here without them.