Low Cost Accoustic Diffusor and Treatments

I just finished setting up my listening room in a home we moved into a couple of months ago. And in the process a local audio installer noticed that my wife had a wooden type drawer and mentioned these work perfectly as diffusors.

You can find these online for $30 per, as compared to $600 per for similar looking panels custom built for the purpose.

I ordered a few on ebay, hung 3 on the back wall, and voila, better imaging and sound staging at a small fraction of the cost.

And the best part about it, was my wife, (a graphic designer) hung them for me she thought it was such a great idea.

Any other low cost, and attractive acoustic treatments you've used to tame your listening room?