1. A targeting system configured to generate a set of targeting keywords that target a specific offer to a desired audience, the system comprising: a targeting server configured to obtain data from at least one server that forms part of an online social network, where the obtained data describes member profiles of members of the online social network and activities performed on the online social network that are associated with the member profiles; wherein the targeting server is configured to detect affinities between a member profile and one or more keywords based upon data describing activities associated with the member profile; wherein the targeting server is configured to generate a database containing the member profiles and associating detected affinities between member profiles and keywords; wherein the targeting server is configured to identify member profiles within the database that are associated with an affinity to at least one offer keyword; wherein the targeting server is configured to identify other keywords for which the identified member profiles have an associated affinity; and wherein the targeting server is configured to select a set of keywords including at least one of the identified keywords as targeting keywords for the specific offer, where the selected keywords target the desired audience for the specific offer.