Adobe's User-to-User (u2u) forums.  There are many, covering most CS products and more.  Root url is   < http://forums.adobe.com/>.

Following are the Photoshop related ones I find most useful.

  http://forums.adobe.com/community/cameraraw

Eric Chan, Adobe camera Raw engineer is a frequent contributor to this forum.  While forum is titled Camera Raw, functions discussed are essentially identical to their equivalent in LR's Develop function (with a different UI).

  http://forums.adobe.com/community/bridge/bridge_windows
  http://forums.adobe.com/community/photoshop/photoshop_windows

(There are forums for both mac and windows.)
Chris Cox, longtime Photoshop engineer, is a frequent contributor to the Photoshop forums..

  http://forums.adobe.com/community/lightroom

Forum title is "Photoshop Lightroom."  I'm not a Lightroom user; I've been a Photoshop user since Photoshop 3 and the original camera raw 1.0 that was re;eased as an add-on to Photoshop 7 in 2003.  But I have several friends who are Lightroom users so I like to try to learn and understand a bit about LR to be able to converse with them.  (Thus my interest in last night's session.)

And one more Adobe blog in addition to John Nack's excellent one, this from Julieanne Kost:

http://blogs.adobe.com/jkost