Arduinos rock. They're basically cheap, programmable circuit boards that have an awesome interface. You can do some really cool stuff with them - in the past, I've made a matrix of infrared LEDs that can turn most brands of TV off, as well as a intervalometer.
I really don't get enough time to tinker with stuff like this. With a bit of effort and very little cash, you can create some really awesome kit. It's always nice to crack out now and then though.
- Sony DSLR-A230