Now here’s a good use of technology:  The Flo Control Project.  The guy’s using a digital camera hooked to a computer to take a picture of his cat Flo on the way into the house.  If the picture compares favorably with a picture on file, then the cat’s door is unlocked.  If the cat is carrying a mouse or a bird or other present, or if the cat at the door isn’t really the cat, then the door remains locked.  This is very cool stuff, and the web site gives a very good explanation of how it works.  Well worth the read.