Linky- windows, mac and linux (tar.gz for now on the main site, I have not checked any repositories) versions available. http://fold.it/portal/ Do play through the tutorials and poking around their wiki is a good idea as well http://foldit.wikia.com/wiki/FoldIt_Wiki I was pointed towards this earlier today- it works like fold@home but with the idea that even a poor human brain is somewhat more powerful than the best supercomputer. For me at least gameplay is what would happen if tetris met a 3d crayon physics, picross and the most addictive flash/XBLA/similar game I have ever played. Not to mention it is for science as well. Obviously it is not going to be doing serious work protein folding as far as the end user sees but it does allow you to fiddle with a nice approximation of it, if you want to play serious business biological science you are pointed to http://biopuppy.org/ instead.