DirSpy allows you to see all those using network files within a specific directory.

Other impressive features of DirSpy include extensive server/client information, volume information, volume disk space monitoring, directory information, deleted file information, the ability to salvage and purge deleted files, tree diagram of network, see who is online for a particular server, see the connected/disconnected servers for the current user, send messages to users, clear connections of users, query the network for user names, change user passwords and much much more!