Expand your Guitar Hero music library for iPhone and iPod Touch as four new track packs have been released. The first pack includes Interpol's "Obstacle 1," "Valerie Loves Me" by Material Issue and Spoon's "I Turn My Camera On." The second track pack features the song "Saviour" by Dredg, "Hash Pipe" by Weezer and Spoon's "Trouble Comes Running." Lynyrd Skynyrd's "What's Your Name?" lands on the third pack, as well as "Stuck In the Middle With You" by Stealers Wheel and "Wipe Out" by The Surfaris.

As a bonus, Guitar Hero developer, Vicarious Visions, will be offering a free two song track pack as part of a special "VV Thanks the Fans" track pack. This pack includes "Fuzzy Dice & Neon Headlights" by Scharling and Sentient Machine's "James Brown New Year's Eve Bash."

For those of you who do not have a copy of this app on your iPhone or iPod Touch, you can pick it up at the App Store for $2.99 at this link. Track packs are only available through the Guitar Hero app and cost $1.99 each.