I think you could call it the world's smallest computer, which is about credit card size.
A little more powerful than my first computer (6502 CPU) which ran at 1-2MHz (Max) with 16Kb RAM, and was a LOT BIGGER.
It's a Linux-based computer that can plug straight into your TV and is capable of just about anything a regular Computer can do. Some Office applications (Word processing, Spreadsheets), light gaming and even capable of HD video, and because it’s open-source, anyone with programming knowledge can do what they like.
There are 2 models (Model A & Model B), costing around $30 & $40 (AUD). Model A features 256Mb of RAM, one USB port and no Ethernet port, while model B features 512Mb of RAM, an extra USB and an Ethernet port.The organisation labels themselves as a charity whose vision is to bring Raspberry Pi’s to kids all over the world to teach them programming skills.
Here's the link for the organisation producing these things - Raspberrypi.org