I just bought Creative's new (to the USA) HN-700 noise cancelling phones. They're great. Tight on the ears, a slight hiss, but the noise cancelling is fine. They have a generic 3.5 mm detachable cable. $69 plus shipping from the creative website. I think they are the same product as the Plane Quiet Solitude.
I also tried the Kensington 33084, but they weren't as good. (I think these are the same as the Plane Quiet NC-6).