There’s a forum for AD&D 1st edition, a forum for OD&D, and kind of a forum for 3rd edition, but even though Basic has become pretty much the standard for OSR games these days, there doesn’t seem to be any forum specifically dedicated to that. Sometimes I look at the forums of specific retroclones or the Basic sections at Dragonsfoot or Giant in the Playground, but all of these have pretty much negligible activity.
I could set up one myself. I’ve been forum admin before and was able to set up this site and mediawiki, so from the technical side it shouldn’t be a problem. But would anyone care?