The Etymotic Logic ER-4S's are by far the best I've heard. I prefer them to the Sennheiser HD-600's and 650's (w/Cardas cable upgrade). Detailed, extended and neutral, with a nice, intimate "head space." The foam ear pads work best for me.
The Sennheiser MX-500 earbuds, at $20, are the best cheap headphones I've used.
The Sennheiser MX-500 earbuds, at $20, are the best cheap headphones I've used.