Variable-Speed Free Rhythm Tracks

pdg

http://www.fbbts.com/Gypsytunes.html

Pretty sure everyone knows about these, but they're great! You can change the tempo in 5% increments, and there's a looping option; also an option to hear solos (I guess so that you can sometimes play rhythm).

Only drawback is the limited number of songs.

Buco

They sound like bandinabox tracks.

Edit: it says exactly that in the about section.