Room Treatment

We have all talked about the best amp, best pre-amp and the best audio components to buy at a certain price. I would like to find out what material is the best room treatment available. Is is a hard material like a styrofoam product or an absobtive product like rubber or sponge? What has worked for you and why? Do you use fabric to hide these treatments or have you found something better? Room treatment has very little discussion. I would like to find a DIY project that can improve the overall dynamics of a very difficult room. Let me hear your comments.....
I have made rectangular and triangular panels out of 2'x4' fiberglass ceiling tiles and covered them with muslin fabric and a hot glue gun.I also made tube traps out of 4' metal fencing like the type you would put around a garden.I filled the inside with fiberglass insulation,but didn't pack it tight.I left a hole down the middle and then also covered it with the muslin fabric.Not only are these effective but they are also cheap.Good Luck.
After pricing commercial products such as Sonex, I decided to make my own acoustic panels. I have four panels on the wall behind the sweet spot, and they work very well. I used convoluted grey packing foam glued to hardboard panels covered in acoustically transparent white fabric. I got the foam from work, and the perforated fabric from a local store. I can neither measure nor compare my panels' performance with products like Sonex, but for me they work fine. My only regret is that I didn't make more!
Herman,you can buy them at any Home Depot,Lowe's etc.Just remember to put bare fiberglass side out towards the room and cover them with some fabric so you don't have fiberglass particles floating in the air.Good Luck!!!