I hate going on gaf and asking for buying reccomendations, but I've had a hell of a time trying to sort through amazon, heapdhone review sites, and neogaf to try and find stuff that is both (1) still available and (2) fits my requirements.
I'm looking for
*over-ear
*under $300
*don't look too stupid/huge/ridiculous
*noise cancelling (active or passive)
*good build quality (I've had some sennheisers in the past that basically just fall apart eventually)
and of course, good audio quality. I listen to pretty much everything from spoken word, classical, rap, rock, vocal, lofi, etc.
For cheap noise cancelling with a good sound you could definitely do a lot worse than the Logitech UE6000. They are discontinued now but used to be on Tyll's Wall of Fame at Innerfidelity.
I picked up a pair on Ebay for $45 (they sold for $200 new) and am enjoying them. For example, I used them today while vacuuming the house and was able to really hear and enjoy the music out of my iPod Touch. The noise cancelling uses 2 AAA batteries but that can be toggled with a little button on top of the headphones.
They are over ear and to me they look a little bit space age (like most Logitech stuff) but are not overly large. They fold up nicely and come with a carrying pouch so they make a great mobile set.