I work for a film VFX company and we utilise several hundred Linux machines to render all of our work. This can involve using multiple machines to work on one single frame, or to render a batch of frames. We can't utilise all the memory all at once as you suggest, but by splitting the job into smaller chunks then we can get the work done much quicker

Regards,

Martyn

There are (at least) 3 on-line distributed computing sites that work by using your spare cycles:
The most famous is seti@home which is looking for inteligent signals from space
http://setiathome.ssl.berkeley.edu

folding@home which tests protein folding
http://www.stanford.edu/group/pandegroup/folding/

climates.net which, umm.. runs climate projections
http://climateprediction.net/

I am sure there are more but these are just the ones I have found. Seti@home will run on anything but the other 2 need 1+gigahz to run

GrimJack