A website that would get together people who can review code and people who need code reviewed.
New to a language, library or toolkit having someone review your code can be extremely useful. Paying someone to go through your code and writeup notes on bugs, use of deprecated api, bad api, security bugs, code style can very valuable. When releasing a library having an API expert read through your api or a security expert look over for any issues can help.
It could be karma based, it could be actual $, not sure. Getting people used to the idea that they are writing code to be read by a human and that a human will review everything is a good thing.