Business oppty: Site for members of a group to share recommendations

I subscribe to multiple email lists that are restricted to alums of Columbia Business School. The New York list is particularly active and I've used it myself to get recommendations on a primary care physician, accountant, and health insurance broker.

Alums frequently post looking for a lawyer who can handle XYZ type of case, a good web designer, a company expert in importing fabric from Taiwan, a capable nanny - all things that are tough to research online.

There seems to be a business opportunity here - at least there is a felt need that is not being suitably satisfied.

I know there is Angie's List, which allows users to post reviews of doctors and contractors and so forth, but I want a review site where I can see reviews by people I trust. Either reviews by my friends or reviews by members of an affinity group - such as alums of my college or business school or McKinsey.

This seems like a feature that could be incorporated into LinkedIn or Facebook - perhaps sold to them once developed.

I know that LinkedIn has recommendations, but that is for folks that you are connected to, and it requires too much work having to do a write-up.

It would be good if I could put it my recommendations on, say, LinkedIn for all the professionals I recommend (doctors, accountants, web people, etc.), and then people in any of the groups that I belong to would be able to see those recommendations.

Maybe this website already exists somewhere. Often when I come up with an idea like this I'm pleased to find that someone has already created it. If you find it, please let me know in a comment.