You know that red bar that hooks onto your car steering wheel to discourage thieves, Fake TV does the same thing by making it look like someone is home with a flashing plastic box that replicates not just any TV, but a 'real LCD HDTV' .
Sure, you could just leave your actual TV on, but that would be a blatant waste of electricity. Energy wise, Fake TV is equivalent to leaving a night light on. A built in timer also turns the TV on and off automatically, so no need for an external timer there. Just make sure that the box can't be seen from the outside and this is actually a pretty good deterrent.
Available here for $39.98.