1. A method of applying metadata to a document for improving subsequent document retrieval, comprising: receiving a document via an operating system user interface; providing one or more flag types for application to the document; receiving a selection of one of the one or more flag types for application to the document; saving a metadata associated with the selected flag type to the document; establishing a reference relationship between the document and the selected flag type; receiving a search request via the operating system user interface for any data items related to the selected flag; discovering the metadata associated with the selected flag type saved to the document; and returning the document in response to the search request.