1. A computer-implemented user interface method of submitting search requests to at least two search engines and presenting search results therefrom customized using content preferences learned about a user, the method comprising: sending query information to the at least two search engines, the query information including (a) a query identifying desired content, and (b) user information, the user information including (i) context information describing the environment in which the query information is being sent, the context information adapted into a syntax understandable by at least one of the at least two search engines, and (ii) a user signature representing content preferences learned about the user; receiving at least one set of a search result and auxiliary information from the at least one of the at least two search engines in response to sending the query information, the auxiliary information of the set including information describing attributes of the search result of the set that led to the search result being chosen by the at least one of the at least two search engines; ordering the at least one search result based at least in part on the auxiliary information; and presenting the ordered search results to the user.
8. The method of claim 1 , wherein the content preferences learned about the user include at least one of a user profile, user behavior, and user activity.