I have written a pretty extensive webapp and it is going to go live in the next fews weeks and before I really publicize it I want to get some professionals to review it for optimization and best practices. Is there any online service or way to find local software engineers who would be willing to do this?

Just to give some specifics that may be helpful, my site is on Google App Engine and written in Python and it is tough to find someone with extensive experience in that area.