If you have a simple Arduino project that uses only a few pins, you might be able to shrink it down to a single 8-pin ATtiny chip. In this video, Matt Richardson shows you how, based on a tutorial from MIT Media Lab’s High-Low Tech Group. The best part is you can use the same Arduino code and development environment that you’re already used to.
More information about this how-to is available at:
http://blog.makezine.com/archive/2011/10/how-to-shrinkify-your-arduino-projects.html