1. A method operable on a computer for inferring a user's interests from user generated tags, the method comprising: collecting a plurality of user-generated tags from a given user and one or more users in a social network of the given user over a predetermined period of time; electronically, calculating, via a processing device, a corresponding z-score for each of the plurality of user-generated tags, where the corresponding z-score is a measure of a statistical significance for a given tag based on an observed frequency of the given tag being selected and a tag selection frequency distribution over the plurality of user-generated tags for the predetermined period of time; retaining one or more tags from the plurality of user-generated tags where the corresponding z-score of the one or more tags is higher than a threshold determined based on random tag selection by the given user and the one or more users in the social network of the given user based on the tag selection frequency distribution; comparing the retained one or more tags of the given user with the retained one or more tags of the one or more users in the social network of the given user; and inferring the given user's interest based on the comparison of the retained one or more tags of the given user and the retained one or more tags of the one or more users in the social network of the given user.