FiveCat:
You are a clever guy/girl!  Using 'critique group' as a key word would certainly work for me -  I dont always use key words, and even when I do, nothing to stop me from adding another one.
Slightly annoyed I didnt think about it :)
I guess you cant subscribe to it and get e-bot notifications, but you can search for it when you have time to view &critique and when you are browsing you can check that the posting person actually wants critique rather than just meaningless comliments.
I would say its the best offer so far.

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
http://artpearl.redbubble.com/