Pandora is a good app.. my husband just got the iphone, and we both use
www.pandora.com for music ... it's free internet radio, start by putting in music you like, then it recommends songs you may or may not like.. you thumbs up or thumbs down them, and in about 2 weeks of use the player learns you and plays music it thinks you like.. its really cool.. And you can access the same account via computer or the iphone.