I don't know if this website has been discussed here before, but I just found it and it's a fantastic resource! Can be a bit technical, but very readable. In particular the 'Articles and Demos', 'Audio FAQ' and 'Downloads' are full of thought-provoking information. I'm still reading... Digido. Not all is directly relevant to the listener, but plenty to absorb. I recommend a look.

No responses, maybe the site is a bit intimidating. Well, how about a specific. I like the Subwoofer article (Media/Articles and Demos/Bob Katz/Item 17). He believes in the 'listening' approach rather than relying too much on instruments. His use of 1/3 octave pink noise for sub/sat integration is one that I hadn't seen. All-in-all a very thoughtful approach.