Wow… I was just discussing this the other day. I was looking to find some sort of material to reduce the noise of my computer. It’s a pretty massive rig: full tower, 4 case fans, big power supply fan and a Dragon Orb CPU fan. It produces quite a lot of noise and it makes it a bit hard to enjoy watching a DVD or playing games for long periods of time. This might be the solution. It’s a non-insulating (doesn’t trap or produce heat) sound reducing material designed for PC cases. It’s called Pax.Mate and it’s from Akasa.
I took a look around and found a few more reviews. Apparently its good stuff and I can buy it at CoolerGuys, who I like. This may be a very near future purchase.