SeeqPod Mobile is being offered free until December 21. Normally its $9.95. If you've never used SeeqPod, it's basically a search engine for mp3s. When you get a hit on a song title, the song will play in the application (streamed). It's pretty handy when you are thinking of a song and want to hear it right away.
The mobile app looks pretty interesting - they load up regularly updated playlists for you automatically.
http://www.seeqpod.com/mobile/