How do I dampen my listening environment?

Here are some links for you regarding acoustical panels :

http://www.gikacoustics.com/

http://www.acousticalsolutions.com/acoustical-wall-panels

If you want to check out more sites, just do a google search under " acoustical panels ".

With a hose? :)

See if you could find where the sound is reflecting from the floor, to the walls and possibly back to you now.Somebody had an idea on here about using mirrors to visualize where the reflections are coming from.I'm not sure of the method that they described though.It may have been if you could see the reflection of the speaker,the sound would do the same?Possibly walking around and see if you find the reflected sound.Maybe temporarily taping panels in those spots. Hopefully the tape won't remove the new paint.Or have someone hold a sound absorbing panel in the spots you suspect.

They also have foam mattress covers($10 ballpark) you could cut and use to experiment with.♫

Here are a couple other web sites with good products:
ATS Acoustics
Auralex
I am using products from both. The panel I received from ATS seemed well made and arrived very quickly. You could also go the DIY route but I think it's hard to beat the prices of these products even with DIY. Good luck.