RefactorMyCode.com is a great site for this very purpose. It was launched recently, I believe, but is already very popular for different languages. I suspect this is the site you are looking for.
If you have not met yet, the site design is centered around the possibility of anyone who comes and offers additional improvements to your code, with comments. There is also a built-in reputation / ranking system.
And yes, the aesthetics of the site are sorely lacking, although the concept and functionality are still wonderful, in my opinion.