Actually reviewing ranks are already in works, as far as I know.

I wouldn't do post count ranks though.

I post something because I like to post, and maybe something does interest me.

If a thread isn't interesting to me I don't post in it.

Other than that, I agree with Link.

EDIT:

Something I forgot about reviews.

Everybody who thinks there are too less reviews, have you ever thought about MAKING REVIEWS YOURSELF THEN?