1. A method for sending a message in a social network, the method comprising: receiving from a source of the message or from a user a keyword relating to a subject of the message; retrieving from an ontology source a normalized set of concepts associated with the keyword, wherein the ontology source comprises at least one community-generated ontology source; collecting information from the social network, the information comprising one or more interactions between users of the social network and profile information for the users; identifying a subset of the information that corresponds to the normalized set of concepts, wherein the subset of the information is used to form a global topic model comprising at least one topic; sending the message to at least one of the users of the social network who is associated with the at least one topic; and dynamically updating the global topic model as new information is collected from the social network, wherein at least one of: the retrieving, the collecting, the identifying, or the dynamically updating is performed using a processor.