In the same vein as Pandora, Slacker Radio is a personalized radio app for Windows Mobile 7. The UI is a little sleeker and more stylized than Pandora, and you can also access song lyrics for any song that gets played (just in case you ever have one of those friendly arguments over a song that just needs to be settled immediately). You can also browse through a featured music section to get more musical inspiration once your current stable of favorites gets a little stale. Be sure to check out the over 130 programmed genre stations, in addition to ones based around the songs or artists you search for. The whole package is totally free, so why not check it out?