1. A computer-implemented method for sharing annotated content with an annotating user, comprising: receiving from a user a first set of keywords for annotating content from the annotating user; receiving from a user a second set of keywords that designate whether the annotated content annotated by at least one keyword included in the second set of keywords is shared with the annotating user; storing in a data store a first association of the first set of keywords with the annotating user, and a second association of to second set of keywords with the annotating user; receiving via a client system, which is associated with the annotating user, a keyword selection for a select keyword and an identifier for the annotating user; retrieving the first and second associations from the data store; determining from the first association and the identifier whether the annotated content from the annotating user is annotated by at least one keyword in the first set of keywords; determining from the second association whether the select keyword is included in the second set of keywords; and displaying on the client system content annotated by the select keyword if the annotated content from the annotating user is annotated by at least one keyword in the first set of keywords, and if the select keyword is included in the second set of keywords.
9. The method according to claim 1 . wherein the user is a computer.