Just a brief plug before I'll write the actual article.
I have revamped and republished Magic Player.
It is an app which you can use to listen to Jamendo provided music.
I hold a complete index of Jamendo songs on my own server and the application uses my server to get random songs to play.
You may rate the songs. It will save the rating and the time in the song it was rated. Feel free to rate multiple times per song!
Currently the rating data is not used for anything, but I plan to use it in the future to try and select song which are similar to those you have rated highly before. I'll plan to use tags, genres and user cross-comparisons to do this.
So, anyway, give it a try: