Here’s an interesting use of technology. Kimberly Nixon and her husband rigged up a very special cat door for their two cats Gus and Penny. Apparently the neighborhood cats were helping themselves to Gus and Penny’s food, so Kimberly’s husband, a programmer who likes to build stuff, created a cat door with an RFID reader. Each cat has an RFID tag on its collar. When the cat gets close to the door, the reader reads the tag and opens the door. This keeps the neighborhood cats out of the food. Then, to keep track of Gus and Penny’s whereabouts, the whole contraption is connected to an old laptop which has software installed that snaps a photo of the cat entering or exiting the door (see images above) and then posts a message along with the picture to Twitter. Brilliant!