I'm using an iphone 4, and recently decided I'd like to listen to music when I walk or run. Never really used a phone for music before, so new to this world. The two options I've figured out so far, listening to songs from my itunes library, or listening to 'radio stations' playing the type of music I like, both have drawbacks -- I'm sick of my itunes library songs, and the radio stations have commercials, get spotty reception while out wandering around and can be otherwise glitchy, and don't have tons of songs anyway. My ideal scenario is some app or service that provides a huge collection of commerical-free music in the genres I'm interested in, such as 1960's rock and roll, or 70's pop music, with no reception or listening quality issues, and ideally one where I can skip the songs I don't like. My cable TV offers something similar to this, commerical free music stations playing random songs in different genres. I like it a lot, although I can't fast forward. Anything similar available for iphone?