I'm at the Gordon conference on Atomic and Molecular interactions right now, having lots of fun. For instance, here in Colby-Sawyer College they've got "hands free towel machines" in bathrooms:
(sorry for blurry picture)
In the bottom of this thing there is an infrared trigger that rolls out the towel if you put your hand close to it.
The problem is that water absorbs infrared, and this machine works well only if your hands are already dry.