Click here to Buy it Now from the Apple App Store, $20

StompBox should look familiar: Apple used it in one of its iPad 2 commercials to illustrate how the tablet can be used to make music. The app puts the power of a professional digital effects unit in your tablet. Create your own custom guitar effects by patching together any of the 17 digital effect modules-delay, reverb, flanger, phaser, chorus, pitch shifter, and others-that you can save for later use. StompBox also includes the ability to record four-track loops, and playback through an external amp. All you need to do is connect your guitar and get to work.