1. A method for a service recommendation service, comprising: Determining a first set of queries that do not expose additional data items stored in a data source of a participant in a collaborative information system than are exposed by queries already implemented on the participant's data source; Identifying a first set of query services that are not authorized to involve the data source, but which use the determined one or more queries; and Recommending the first set of identified query services to the participant; Determining a second set of queries used by authorized query services of the collaborative information system and implemented on the data source, some portion of the data source being made available to the queries used by the authorized query services; Identifying a second set of query services that are not authorized to involve the data source, but which use the queries already implemented on the data source; Observing data items stored in the data source from statements of the second set of query services; Determining, from the observed data items, additional queries that are not implemented on the data source, which search the observed data items; Identifying additional query service that are not authorized to involve the data source, but which use the additional queries; and Recommended the identified additional query services to the participant.