I also uploaded a backing track to my SoundClick site just yesterday.. it is a basic 12-bar blues piece albeit a little slower than normal. I have even put an example of what is possible with it as well.

http://www.soundclick.com/bands/pagemusic.cfm?bandID=737179

If you want to use it, make sure you download the MP3 of the Jam Backing Track it has a free, creative commons license so you can use it for whatever you want without infringing on copyright.. Most of the other tracks do not have a free license but you can still listen to them.