Our computers have down time like everyone else. Unlike people, however, computers can be made to work during their idle moments and, for example, contribute towards saving the world or calculate mathematical problems of terrifying complexity.
The most unfathomable for the likes of oiks like me who failed her maths 'O' level first time is the Distributed.net site. Computers will work on projects, for example, one called the OGR project which: In the first year of running the OGR-25 project has attracted around 55 000 participants with three to four thousand participants reporting each day. The project is approaching 6000 participating teams of which almost 1000 are active each day. So far we have tested over 7 000 000 000 Gnodes of OGR-25 stubs. Jolly good! Only for geeks that one, I feel.
For those of us who prefer to understand what our computers are up to so we can chat about it to our mothers, you could try the World Community Grid which aims to create the largest grid helping humanity. They do research into AIDS and the human proteome.
Google is also partipating in idle time projects; the nonprofit Folding@home project at Stanford University which sets out to model the geometric structure of proteins.
One site, Distributed Computing lists a number of projects based on medical research and other scientific projects such as climate change that you can set your pc to work on. It's a pretty comprehensive site on scientific programmes.
Other suggestions include breaking the Enigma codes sent by the Germans in 1942. Three messages were sent, one of which has been broken. Information on how the project came into existence with some of the problems encountered can be found at Cnet news.
My favourite, being the flippant person I am, however, has to be the The Bank of Time where you can save your idle time in a screensaver visualising it by growing plants, and as more people participate, they will soon be able to learn whose computers have been the most idle and which organisations have been slacking. Funnily enough, it's funded by the Arts Council of England. The site was actually nominated for a BAFTA. It strikes me as being a peculiarly British idea. Read their press release for more information.
Mary Mary quite contrary
How does your garden grow?
With idle time from drinking tea
And pretty z's all in a row...