1. A system for sharing information useful in building queries, comprising: an annotation database for storing annotations; a query building interface allowing users to build queries by specifying query components, wherein the query components are stored and are accessible to the query building interface; and an annotation system allowing users to create and display annotations associated with query components used in building queries, wherein the annotation system provides an annotation creating interface allowing a user to create an annotation for a query component selected from the query building interface, wherein the indication is an annotation icon; and wherein the annotation system is configured to: display an annotation associated with a query component, in response to a user selecting the annotation icon, display, to the user, a suggested substitution for the query component associated with the annotation, and replace the query component associated with the annotation with the suggested substitution, in response to the user accepting the suggested substitution.