I think this is a pretty helpful and friendly crowd for most any question (though there are a few hotspots).

I think Haoleb is right- Etymolic is very highly regarded. I think, though, they're more known for canal phones? Anyway, this might be something helpful: http://www.arstechnica.com/reviews/004/headphones/headphones-1.html

Arstechnica is a great place for info. This is a roundup of some good portable headphones (various technologies).