17. A computer-implemented system for determining similar users comprising: a non-transitory memory; and said system operable to: receive information for a source user, the information including at least one topic and a user value for each topic, where: the user value represents how strongly the user is associated with that topic, and the user value includes a user authority value representing a user expertise related to that topic and a user interest value representing a degree of user association with that topic; generate similarity scores based on a user value for each topic for the source user and a user value for the same topic for each user in a set of users, where each user in the set of users is associated with a user value for each topic; select one or more similar users based on the generated similarity scores; output one or more of the selected users; and output the identity of one or more overlapping topics and a value indicating a degree of overlap for each overlapping topic.
17. A computer-implemented system for determining similar users comprising: a non-transitory memory; and said system operable to: receive information for a source user, the information including at least one topic and a user value for each topic, where: the user value represents how strongly the user is associated with that topic, and the user value includes a user authority value representing a user expertise related to that topic and a user interest value representing a degree of user association with that topic; generate similarity scores based on a user value for each topic for the source user and a user value for the same topic for each user in a set of users, where each user in the set of users is associated with a user value for each topic; select one or more similar users based on the generated similarity scores; output one or more of the selected users; and output the identity of one or more overlapping topics and a value indicating a degree of overlap for each overlapping topic. 18. The method of claim 17 , wherein to generate similarity scores, said system is to compute a cosine similarity of user values for each topic.