I’m not a great singer or player but these two tracks (featured in acappella section) are quite poppy and are recorded to a drum machine for easy reworking. As well as the acappella the various backing track files are provided too.

http://ccmixter.org/files/s...

http://ccmixter.org/files/s...

Don’t forget there’s some more totally free stuff in multitrack form at http://www.jamendo.com/en/a...