I've actually been thinking about offering a code review service, since it would fit well with the way I like to work. Personally, I wouldn't want to do one-hour reviews, but would be very happy selling four hour blocks of my time.

A third-party code review could easily point out certain problems that aren't only qualitative (e.g., the code is vulnerable to SQL injection attacks). It could also be useful to evaluate programmers. The project owner hires a few different developers to write a single user story, the reviewer tells them which code is the highest quality, and the project owner hires the best coder to do the complete project. For slightly more corporate clients, it could also be used to identify to a non-technical manager where their programmers need additional training.

As far as the reviewer being asked, "How do I fix it?", that could lead to the reviewer offering training material, libraries, or development tools.