It's for grid computing. They do the hard work so all the scientists need to do is write the science part. Simple enough?

BOINC ( Berkeley Open Infrastructure for Network Computing) has a website, http://boinc.berkeley.edu/. They create software that people can download onto their computers in order to participate in scientific projects. The software works by downloading data from the scientists, then it processes the data and sends the answers back to the scientists, and requests additional work. It's done all in the background using the spare power designed into but not currently being utilized by your computer. The software even enables you to participate in multiple projects of your choice. When enough people sign up for these projects, the scientists eventually have more computing power at their disposal than the world's largest supercomputer can provide.