Sigh... Let's contain the clocks to their own area, shall we? There's a specific question at hand here.

There are some good rules of thumb for sound treatment. Corners are often good places to start, as are the first reflection points (which can be determined with some analysis of the room geometry or even just a mirror to find points on the wall where you can see a reflection of the speaker from the "sweet spot"). You can get very carried away with it, but most folks who have dug into it find that the first few panels (when properly placed) yield the greatest benefit.

A couple sites that have cropped up around here as useful resources for both information and the panels themselves are GIK Acoustics (which has a pretty detailed FAQ ), RealTraps (which also has a good HowTo page), and Auralex . The traps in wingnut\'s system are from RealTraps, and stabie has some Auralex stuff.