What are the best Room Accustic Treaments members have found?

+1 on GIK.

Jim Smith's "Getting Better Sound" is a handy reference for room optimization.

I've been working on The Room for the last year or so, I found a set of eight Aurelex 2' x 2' foam studio panels on line, made some cheap stands/frames to hold them up, got four concrete forming tubes, and moved these around the room to figure out what should go where, before buying from GIK. 

One problem I am not yet sure how best to solve is my front wall has a 6' x 6' window.  Initially I put up huge heavy drapes, which made for a nice dark background (both acoustically and visually), but as time went on I realized I missed the light, and also when I opened the drapes but left the blinds closed, it seemed to make for bigger sound stage.  And after 1.5 years, I realized that the drapes are fugly.  So I plan to buy some cellular shades plus a textured wood blind that will raise/lower over the blinds, hopefully have the choice and best of both worlds.  Might be TMI, but that's my room story so far.  Oh, and I dumped the rack in the front of the room, that was an instant improvement, probs bc it was Ikea.

If aesthetics are not a priority and you can live with the look of unfinished foam this is an inexpensive possibility:
http://www.nextacoustics.com/

The company I used is Audimute.I sent them a layout of my room with pictures and they advised me what I needed. Their stuff is also made to order and their prices are reasonable. Never talked to anyone personally, all emails were promptly replied, and I found their quality to be excellent.

I will add to the list of supporters for GIK products. I have found the products attractive with a good selection of fabric colors, fairly priced, great customer support and quick delivery. Some of the pieces are large and appear that they would be heavy, but in reality are very light for their size.
I suggest going with bass traps in the front corners and two side panels for mounting on both side walls slightly in front of each speaker (first reflection point) as a first starting point.
If you sit very close to the rear wall then you probably should add another wall panel right behind your head centered on that wall assuming you are sitting centered to the wall.
The wall panels in my opinion should be the thicker ones to cover a fuller frequency range. The thin ones are mainly for the higher frequencies.
This should get you started with a quality product.

I have one of the newer Stillpoints Apertures placed on the floor between and slightly behind my speakers.  Helps to focus the image and enhances coherency of the whole presentation. I enthusiastically recommend giving it a listen. Domestically, I appreciate being able to easily slide it away next to my equipment rack when not listening.