This Kwikset deadbolt door lock has a sensor beneath the lock cylinder, allowing you to program the lock to read fingertips to unlock the door. The door can "learn" 50 people's fingertips. Need a handyman? You can program his fingertip into the lock for one day, and deny him access later. And you can still use a good, old-fashioned key if you prefer.
Power inverter for charging your laptop (and other electronics) in your car. This DC-to-AC power inverter plugs into your car’s power outlet, sits in your car cupholder, and gives you two AC outlets (plus a USB port), so you can charge your laptop during road trips.