Directories can help educators find colleagues, resources, networks and tools.

There WAS an Avatar Directory called Avatars United, sort of like a FaceBook for avatars, but it has been disbanded.

There is a directory of HyperGrid enabled OpenSim worlds called Hyperica

The Education Directory for Second Life has institutions using Second Life for educational purposes including higher ed, K-12, community colleges, consotia, institutes of technology, trade schools and libraries.

Lehigh collection of sites in Second lIfe.