As a member of Hack Pittsburgh, our local hackerspace, one thing I’ve wanted to know if anyone else is there before I make the trek over. Well, so did Andy Leer and Marty McGuire, so they decided to build a shop presence notification system. They reasoned that they could measure the ambient light level to determine if someone was around, because people tend to turn on the lights when they show up. With this in mind, they hooked up a photocell to a donated iobridge module, and had a notification widget up on the website in record time. Excellent work!