Arduino Duemilanove
Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.
Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. [Source]
My first one arrived on 08th January 2009. I have been messing with it since. I will be posting a list projects later - just wanted to get the first post up here.