iStomp
You could carry around a huge array of stomp pedals from show to show, or you could carry one iStomp ($150). This simple box works just like a traditional stompbox, only the effects it provides come from your iPhone or iPad. Simply download and select the pedal you want from the Stomp Shop, then load it onto the iStomp — since you actually load it onto the pedal, you don't need to keep your device hooked up, and with true stereo inputs and outputs and four control knobs, you can get just the sound you're looking for. Use one by itself or string multiple boxes together for truly crazy effects.