1. A computer method for determining knowledgeable and available contacts in an instant messaging system, the method comprising the actions of: receiving a keyword related to an area of expertise; searching for the keyword in correspondence of users of an instant messaging system, the correspondence including real-time and historical information associated with each user of the instant messaging system; identifying, based on results of the searching, a plurality of users having used the keyword in the correspondence; determining an availability of each of the identified plurality of users; and ranking the identified plurality of users based on predefined criteria, the predefined criteria including at least one of the determined availability of each of the identified plurality of users, and an incidence of the keyword in correspondence of each of the identified plurality of users, the incidence including both a number and a location of the keyword in the correspondence, wherein the keyword located near a beginning of the correspondence indicates a greater expertise in the area of expertise than the keyword located near an end of the correspondence.
4. The method of claim 1 , wherein the correspondence includes one or more of: mail files, instant messaging system messages, online chat session exchanges, and discussion forum postings.