What room treatment product have transformed your room or audio system?


I've been researching and looking more into room treatment products. Wondering what product really worked for you?
128x128scar972
GIK Acoustics soffit traps.  Affordable (compared to say ASC Tube traps) and some of the few products that work below 60 Hz very well.
Free standing GIK 244 panels for first reflection points.  The "free standing" version. allows you to move them as desired to tailor the sound. 
Critical drywall  angles on ceiling.
Lambs wool panels at 5 locations woven wool carpet 2 home grown music directors on floor 1 music fan oh and 3 Argent Room Lenses silly for some dilberts inspiring for those with ears and mind. Tom