Documents cited by recognized experts are given extra weight by the SPEAR algorithm developed by Ching Man Au Yeung of the University of Southampton and Michael G. Noll of Germany's Hasso Plattner Institute.
The ranking algorithm called SPEAR (SPamming-resistant Expertise Analysis and Ranking), developed by PhD candidates Ching Man Au Yeung of the University of Southampton and Michael G. Noll of Hasso Plattner Institute, uses mutual reinforcement and time stamps to identify expert contributors to social bookmarking sites and their recommended content.
It sounds like we built a very similar system which was published at CHI2009 in April. Released on the net at http://mrtaggy.com