1. A method of delivering targeted content, comprising: collecting, via at least one tangible processor, user activity data for users during a specified time period; extracting from the user activity data, via the at least one tangible processor, questions asked by the users during the specified time period and storing the questions asked in user profiles for the users; clustering, via the at least one tangible processor, the user profiles based on the questions asked; and delivering, via the at least one tangible processor, targeted content to a subset of the users based on the clustering.