A ranting thread would be a place for people to post their complaints about web design, and also for debates to be carried out. Since noone would be searching that forum for info, you could delete anything more than a few days old.
A reviews forum is where peoples would post their site, and then allow others to nitpick it. I know I'd love that forum .
Please tell me what you think so if you don't like my ideas I can at least be rejected right.