Audiobus is, kind of, the coolest music app in the App Store. It is a mediator, of sorts, that lets one music app interact with another music app. It is really quite extraordinary. Once the app is downloaded to your device, it finds all compatible apps and gives you easy access to each one. Not only that, these music apps can now interact with each other. So, you can start a drum beat with FunkBox Drum Machine, add a sample using Loopy HD, plug in your guitar and add some tasty riffs with AmpliTube, and lay down a smooth melody with GrainBender.