I like to think that my PSU is pretty quiet. It's not silent, and I can't be sure exactly how quiet it is, but when I disconnected all my drives and only had the PSU, CPU, and video card fans going, it was a very nice noise level.

I've got an Antec True550. That's right, quiet and 550W. It's worked great for me so far.

I just saw that you asked for all kinds of noise improvement products. Well, the changes I made specifically to improve noise levels were with my CPU fan/heatsink, and the video card fan/heatsink. I'm certain at this point that my CPU HSF was defective. It was incredibly noisey. I then replaced it with this Zalman HSF and not only is it quite attractive (good for the window in my case), it cools very well and is very quiet. I replaced my AIW 9700's fan because it had a very definite whine to it. I went with Zalman again, and added the optional fan which hardly makes a sound.

Other than that, check out www.silentpcreview.com