The Raspberry Pi
The Rasberry Pi is a tiny computer. (Its just 85.6 x 56 x 21 mm) With a 700MHz ARM processor, 512 MB RAM and Videocore 4 GPU, it’s a fairly beefy tiny computer. It can play 1080p H.264 files without breaking a sweat, making it a great addition to your media center.
There are numerous Linux build that will run on the hardware, making the Pi a flexible machine for use in robots or as an embedded computer in other types of machines.
The machine is just $35, and can be ordered online today.