I joined a week or so ago and loaded a short story, 'The Choice', to the 'Commercial Short Story' group. Immediately got some honest, useful, friendly crit, plus a suggestion about a market for the story. I sent it electronically to that recommended mainstream publisher, who has accepted it.
I am also a member of the Harper Collins 'Authonomy' review site, but this site is miles better for no-bullshit crit, and friendly members.