Raspberry Pi
Raspberry Pi is a credit-card-sized computer that outputs high-resolution displays via HDMI and includes USB and Ethernet interfaces. It does everything you'd expect a desktop computer to do and also has a hackable circuitry.
The model A retails at $ 25 while B+ retails at $ 35, making it an incredible, hackable, affordable, and most of all, an accessible little device. The Pi has rekindled the hobbyist programmer and led to a whole host of home automation projects. Check out the latest Raspberry Pi home automation projects on the Raspberry Pi Foundation blog (http://bit.ly/pi-ha).