We don't want to call it cheating, but headphones that can double as speakers? Doesn't this sort of paradox generally open a black hole that swallows Earth?
iHome's iHMP5Us are pretty typical closed-cup headphones, save for the fact that you can balance them on the table, fold the earpieces out, hit a magnetic amplifier switch and share your music with the whole room.
Powered by 2 AAA batteries, we immediately assumed that the idea couldn't produce sound that's all that loud. But then we remembered pretty much every trip we've ever taken on public transportation and the tinny ambient music leaking from some past-prime sorority girl's non-ironically electropop-laden playlist (and her crappy earbuds).
Still, while the iHMP5Us will almost certainly produce a respectable volume, they may or may not be of a quality you'd actually enjoy listening to. [iHome]