The non-profit Raspberry Foundation from UK has designed and produced a low-cost computer for educational purposes. The importance of this project is that you have a complete computer (albeit low power) around 30 € + VAT.
The Raspberry Pi user community is growing dramatically and is becoming a device for all types of inventions. See for example the Adafruit blog.
GRN is playing with the device from the beginning (also on sale at the shop) and we are using it for various projects, follow our blog and twitter and see the possibilities you have.