This project is an aggressive solar hot water collection system. The purpose is to collect and store as much heat as possible, regarding it more as energy than heat. The parts are fairly easy to come by, with a few notable exceptions. The overall goal is to offset as much fossil energy as possible with carbon-neutral solar while using the simplest, safest and most user-accessible technologies and techniques available. Useful applications include preheating hot water, heating a house with radiant floor heating, and potentially using Peltier junctions to generate DC electricity.
Also, this is the amazing flyer my good friend Derek Kaplan put together for distribution at the 2011 Kansas City Maker Faire. If you're looking to try building this, the flyer is a good place to start -- the diagram of the trough is for a 2" diameter collector (the standard size for vacuum collection tubes), and is a 1 to 1 representation -- so if you print the flyer on the appropriate printer, you can just cut out the shape, trace it onto a piece of wood and cut your own.