T.C. kinda beat me to it and in more terse terms . . . .
While I'm **partially** in agreement with incrediBill's suggestion, there's a couple issues very difficult to resolve.
Who gets the pay? The reviewer or this site?
If the reviewer, how do you manage that, or moderate, or arbitrate? "rocknbil's review sucked and he didn't tell me a single thing I wanted to hear, so you should ban him and gimme my money back . . . "
Which leads to another problem, we have a wide variety of skill sets here, some who perceive their skills as much better than they really are, but for the most part, many who are far better than they admit. So how does one determine if the reviewer is providing an educated assessement or a simple opinion that may or may not be helpful?
Many of us would offer a "site review" based on our skill sets, one would review for SEO implications, another for accessibility, many for just presentation and layout, how would you define parameters of a "site review?"
I see a can of worms, don't know that it would work.