1. A computer-implemented method comprising: providing an event repository that maintains event information for members of an online community, wherein the event information includes one or more event records that correspond to real world private events, wherein at least one of the one or more event records has an event id that is associated with a tag id, wherein each tag id is associated with a tag, and wherein each event record comprises structured information that: (i) identifies a first user of the online community as an event-author of a private event, and (ii) is restricted to only a group of one or more friends of the event-author in the online community; receiving from a second user of the online community, who is in the group of one or more friends of the first user, a user-designated tag of unstructured metadata, wherein the user-designed tag provides information about a first event record; without modifying the first event record, storing in the event repository, separate from the first event record: (i) the user-designated tag; (ii) an association between the user-designated tag and a tag id; and (iii) an association between the tag id and an event id; receiving from the second user of the online community, a request for retrieving event information, wherein the request specifies a term that matches the user-designated tag; as a result of the request, performing the steps of: searching the event repository for a plurality of event records that are associated with any user-designed tags that match the term, wherein the plurality of records includes the first event record; and returning event information extracted from the plurality of event records to the second user of the online community; wherein the computer-implemented method is performed by one or more computing devices.