A whiny-little-brat silencer. So when there's some little kid screaming and carrying on at the next table in the restaurant, and his parents are taking no notice, you can just *zap* and the kid gets instant laryngitis. Ah, blissful quiet...
A transporter beam, like the ones on Star Trek. I'd love to just be able to beam to work...
A radar detector that can detect instant-on radar even when it's off.
An anti-tailgating device. When someone is hanging 2 inches off your back bumper at 75mph on the interstate, it automatically triggers the release of a box of nails onto the road immediately behind your car.
I'll take some of those anti-procrastinating pills too. I've been putting off taking my certification exam for months now. And I could definitely use that He-mote Control!