I occasionally post despite fears of disapproval, but then immediately after posting my anxiety levels will become so uncomfortably high I delete the comment. Perhaps some people have noticed me doing this, but if they knew how anxious I felt I believe they would understand. It's kind of neurotic...

I also have some social anxiety as well. A usual amount, I think. And then I tell myself that posting on Less Wrong (which is not the 'real world') would be good desensitizing training. I think it has helped some, but occasionally it has the opposite effect. I once had a minor panic attack at a conference moments before giving a talk -- not because of the talk, but because I realized I wouldn't be able to delete a comment or a post I just submitted and thought I might regret.

Incidentally, the chances of me making a comment (and leaving it) doesn't correlate as much with my perceived quality of my comments as much as with my anxiety threshold at that time. Since I'm not very good at gauging my anxiety response, I tend to always rewrite my comments more and more conservatively until the first idea is all but lost. Then I'll submit the comment just because I spent so much time on it.

(Please don't respond that I probably shouldn't bother commenting; I kind of know that. I'm curious if the whole thing improves over time.)