The World Community Grid is a distributed system to by-pass the cost of expensive mainframes or supercomputers by using shared, individual computers. See this post for more details of how it works. You download the software, and the grid uses your computer power during the time period that your computer is turned on but not being used. I classified this under the "fun" category, but it really is a humanitarian effort that advances science. Similar programs include Seti@home and Folding@home.
A participatory way of gaining computer power to conduct needed and important research. Are there other ways of using the same concept for Extension programming? A good use of your "down" computer time to advance science.