Ok, shameless plug for Pandora. Ever since I downloaded this app to my iPhone I have listened to them non-stop. I also play it at work. I've tried many online radio stations. RadioParadise is good, 89.5worldwide so is KPPC but this brings it all together to give me what I want when I really want it. It is the internet porn to internet/mobile radio.
It has introduced me to dozens of new songs and bands within my genre's. If none of this makes sense to you then go listen for free. You setup stations based upon song or artist or genre. All brought to you by the genius idea of the Music Genome Project. I cancelled my XM radio in my car to stop paying $11 a month.
Now Pandora has been hit with additional music fees as imposed by recent government regulation. I'm willing to pay $36 dollars a year to support them. You can of course go free and hear a 15 sec commercial every two hours. Still better than crappy XM or old school FM. I paid them $36 to keep them going another year.
Trust me, I'd rather pay for this than public radio (I've since switched to free BBC podcasts). I haven't been this excited about an app since the roll out of Firefox.
Try it out.