Use ultrasonic vibration to decrease drag on a ship in order to burn less fuel
Keep track of how much water and energy you use when you take a shower
led color changing with hashtag on twitter, color changes through rainbow with each tweet
Networked Sound Meters, noise levels in apartments, alerting the noisiest offenders. Exposing the noisiest cities.
Get notifications when you send/receive mail in a physical mailbox.
A mousetrap that lets the pest control companies provide fast response and gather relevant data about vermin control
