i have this weird liking for controllers. not video game controllers, but something that you could feasibly use to connect back to your comp to trigger anything. PVP, vidvox, coge, motion, quartz compositions or anything else that you can think of.
I started with an old school gravis gamepad [basically a usb ps one controller]. I then found a universal game controller to usb adapter at my local wally world for under 10 bucks which opens up a whole world of options. This allowed us to map guitar hero guitars as midi devices and almost any game controller.
An Apple Remote [for those Macs that use to come standard with them] can be purposed with a simple Quartz comp, turning it into a simple MIDI controller.
I thought I'd throw together a small list of some cool devices that can be somehow used to trigger stuff:
NES Controllers
Apple Remote
Nintendo Wiimote
Guitar Hero Axe
More 'professional' line of controllers:
Korg Nano Controllers
Behringer line of various controllers
