Raspberry Pi is a neat little single board computer, developed by Eben Upton, that can be used for all kinds of projects, especially for kids and learning programming. From the FAQ: "The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. It is a capable little computer which can be used in electronics projects, and for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. We want to see it being used by kids all over the world to learn programming." Its costs just US$35.
The normal method of programming is with Python. You'll need a power supply (MicroUSB cable), some other support cables, a mouse and keyboard, an SD memory card, and a host computer, PC or Mac, to get going. The cool factor is that you can get your head around this little single board computer and really make things happen.
Check It Out: Raspberry Pi: An Approachable, Fun Single Board Computer