The OpenSim Hypergrid is an extension to opensim that allows you to link your opensim to other opensims on the internet, and that supports seamless agent transfers among those opensims. It can be used both in standalone mode and in grid mode. The hypergrid is effectively supporting the emergence of a Web of virtual worlds.
OpenSim core developer and hypergrid inventor Crista Lope, Professor of Informatics and Computer Science at University of California.
Links to Grid search systems: