I got these links from guitarbattle.com that has a lot of backing tracks to your fav. songs:

(posted by: chavie)
Satriani :Flying in a blue Dream
http://www.digitalsoundplanet.com/Members/000074332_000002391_proj.mp3

Satriani : Crying (Mp3)
http://www.digitalsoundplanet.com/Members/000094711_000002425_proj.mp3

Satriani : starry night (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002383_proj.mp3

Satriani : The Extremist (mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002389_proj.mp3

Satriani :untill we say goodbye (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002384_proj.mp3

Satriani : Time (mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002385_proj.mp3

Satriani : Memories (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002412_proj.mp3

Satriani : Satch Boogie (MP3)
http://www.digitalsoundplanet.com/Members/000074332_000002416_proj.mp3

Satriani : mystical potato groove thing (MP3)
http://www.digitalsoundplanet.com/Members/000074332_000002418_proj.mp3

Satriani : rubina (MP3)
http://www.digitalsoundplanet.com/Members/000074332_000002419_proj.mp3

satriani : War (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002429_proj.mp3

Van halen : Aint talking about love (??????)
http://www.digitalsoundplanet.com/Members/000074332_000002427_proj.mp3

Led Zeppelin : Communication Breakdown (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002428_proj.mp3

Vai : For the love of god (mp3)
http://www.digitalsoundplanet.com/Members/000074332_000001783_proj.mp3

Vai : the animal (mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002388_proj.mp3

The eagles : hotel califonia (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002394_proj.mp3

Jimi hendrix : Voodoo chile (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002398_proj.mp3

Jimi hendrix : Purple Haze (Mp3)
http://www.digitalsoundplanet.com/Members/000052799_000002400_proj.mp3

eric johson : cliffs of dover (mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002399_proj.mp3

Santana : Blackmagic women (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002402_proj.mp3

Black sabbath : Paranoid (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002404_proj.mp3

Dire straits : Sultans of swing (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002405_proj.mp3

Dream Theater : Overture 1928 (Midi? but its very good)
http://www.digitalsoundplanet.com/Members/000074332_000002406_proj.mp3

Paul gilbert : technical difficulties(pretty good midi)
http://www.digitalsoundplanet.com/Members/000074332_000002407_proj.mp3

Metallica : Enter Sandman (mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002436_proj.mp3

Top Gun theme : (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002437_proj.mp3

Van halen : Running with the devil (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002438_proj.mp3

Jimi Hendrix : all along the watchtower (Mp3)
http://www.digitalsoundplanet.com/Members/000074332_000002439_proj.mp3

Ozzy osbourne : Crazy Train (pretty good midi)
http://www.digitalsoundplanet.com/Members/000074332_000002440_proj.mp3

(Posted by: kirkhammett)
Lots of Vai, and Satch:
http://www.ylor11.freeserve.co.uk/

If anyone know of more links that has backing .mp3 and .midi tracks...please post here :-)

Enjoy! :-)