1. A method for providing a third-party content provider a plurality of potential search queries that may be targeted by a given keyword, comprising: receiving, from a third-party content provider, a request to identify one or more search queries that match a given keyword; identifying a table corresponding to the given keyword, the table including one or more search queries with which at least one third-party content item was selected for display, wherein the selected third-party content item was selected responsive to a bid for the given keyword; determining, from the identified table, one or more search queries that correspond to the given keyword, wherein the determined search queries that correspond to the given keyword are those search queries that can be targeted by the given keyword; and providing, for display, the determined search queries that correspond to given keyword.