Although not the first, Legal Force beta (http://www.legalforce.com) has created an on line clearing house for patents available for licensing or sale. It is possible to list patent subject matter of interest for licensing.
There is also a rating system for the patents explained in a 21 page white paper. The advisors to Legal Force include investors that may be involved in the evaluation of the technology.
The home page lists the patent title, patent number and rating. Clicking on the title discloses the patent abstract. I did not see a search function or index to the listed patents. Perhaps this is being developed.