The Raspberry Pi is a credit-card sized computer running Linux (Fedora, Debian and ArchLinux distributions) that plugs into your TV and a keyboard. The Raspberry Pi Foundation's goal is to see it being used by kids all over the world to learn programming. However, the low-cost $25-35 price tag make it ideal for open-source hardware projects.
It is compatible with many operating systems such as Raspbian, Linux, and many more for the beginner to advanced level computer programmer. You can run word processing and spreadsheets just like a laptop computer, as well as watch High Definition television through its' HDMI port and audio outputs. It is not limited by its physical components, as you can solder other parts to the device, and connect through its' 26 dedicated GPIO pins, which can be infinitely expanded upon.