I haven't found any other online MH support forums nearly as good as this one.

But I also attend IRL support groups to supplement my therapy and PsychCentral. I go to Depression and Bipolar Support Alliance groups--DBSA--if you are interested you can see if there's one in your area at www.dbsalliance.org. Sometimes it helps to be around live people.

Good luck in your search. I too am suffering from debilitating depression.