http://inventgeek.com/Projects/usbairsoftturret/Overview.aspx
A mod to that USB foam missile turret you can purchase.
"These air soft guns shoot a plastic BB at up to 250 FPS and is powerful enough to leave some healthy welts on unsuspecting targets."
Wow, i hope they ship this thing with a disclaimer and goggles. As a paintball player i know how dangerous these speeds can be, this thing WILL take out an eye. Not for office use or anything past the novelty of showing off. I'd go as far as classifying this as a firearm with the potential to have charges laid against the operator. Its one of those toys best left un invented.
note that this is a mod that adds an air soft gun, not a complete product.
Also the air soft guns are restricted in some areas because of exactly what you pointed out.