A service on a computer network that performs centralized searches based on index information transmitted by peer systems to a central site using an agent program running on each peer. Peer systems are directed to each other for the purpose of retrieving files. If none of the peers systems known to contain the files is online (and the file is therefore not available), the request is placed in a queue of file requests maintained by the central site. When a system containing the requested file connects to the service, the requested file is retrieved from that system and then distributed to the other systems which had requested the file.