[Replying to Petros <Petros.Listig@fdrive.com.au>]
heats your water tank etc.: http://gigaom.com/2013/05/24/meet-the-cloud-that-will-keep-you-warm-at-night... Needs 50MB/sec broadband..
On a much smaller scale, my son Andy, when he was younger, had in his bedroom a G5 tower, dual CPU (not just dual core), liquid-cooled, with an 800W power supply. He didn't need a heater -- he could just crank up some grunty computation on cold winter nights. Andy still has that G5 tower, but sadly it died a while back. It's such a beautiful machine. When you see it, you want to kneel down before it and worship it :-). If we ever got it working again, I guess we could install PPC Linux, like I've done on my antique G4 Powerbooks. I wonder what the economics would be of heating your home with say Bitcoin mining... -- Smiles, Les.