18. The system of claim 17 wherein: the user interface is configured to receive requests for similar web pages associated with concept sets from a user, and the request manager is configured to determine the similar web pages based on the concept sets associated with the similar web pages based on the one or more concept set similarity values.
17. The system of claim 1 further comprising: a user interface configured to receive requests for similar concept sets from a user; and a request manager configured to determine the similar concept sets based on one or more concept set similarity values.