Raspberry Pi with CGMiner making the bitcoins.
My Raspberry Pi runs almost 24/7 with some of the projects that we've done in the past such as OpenSIM and installing Airplay onto it so that we can send music to the amplifier to my living room and even running some P2P programs to get my latest Linux distros faster. Because it runs on a 24/7 basis that means that I'm pissing 3 watts of power non-stop. We decided to out my Pi to work on getting me bitcoin currency.