I read this article a couple of days ago, and for the life of me, I can't figure out why I didn't share it with all of you. For the first time, after reading this article, I felt a little inadequate about my hitherto "killer" rig at home. A horrible thing has happened. I have found someone with a better and bigger PC than mine. Ouch.
ExtremeMHz have been busy building something of a leviathan, in their project to get a dual motherboard, water cooled ass-kicker on the go, which you can read about here.
Its worth reading even for their choice of case, which is about the biggest PC case I have ever seen. Heavier metal than that tends to move into the realms of rack mount cabinets (which could contain servers, switches, routers) or small mainframes, etc. The final machine has got some pretty good cooling, and after adding all kinds of things I had never even thought of, they send up with something of a monster.
A well worth read here.