Check out this feature on the Apple website about the Stanford Laptop Orchestra (SLOrk), an ensemble of student computer scientists and musicians that uses 20 MacBooks to compose and perform new music: Stanford Laptop Orchestra (SLOrk): Musical Macs. Very nerdy, but kind of awesome.
The group was founded by composer/researcher/programmer Ge Wang, an assistant professor at Stanford. They use MacBooks (of course), the devices' built-in sensors, and computer science to create synthesized "clicks, chimes and bleeps." You know, music. Watch a video of SLOrk in action here. (Thanks, Henry.)