I do like the "What are you listening to..." thread, even though I haven't posted there for a while.
George's "Nice Photos" thread is always enjoyable to look at, but i'm finding the artistic and technical qualities are now far beyond my capabilities and that might be putting others off contributing as well as myself.
The Hi-fi, Streaming and Home Theatre forums are always full of good, useful information, even if you do have to filter out slight bias and a few cable myths from time to time.
The Padded Cell is aptly named, but generally good-natured. It certainly provides a variety of different points of view. and opens the eyes, if not the mind !!