I am using Client activated remoting. Is there a way to display how many clients are connected to the server? If so, is there a way to display a string into a ListBox from each client that is connected to the server?

You could create another remote object, a singleton SAO, that contains a list of all CAO objects.
The CAO objects (clients)will have to register themselves with the SAO.
You can then create some methods in the SAO object that provides information about registered clients.

Hopefully this helps.
Regards,
Stefan

Have a look at this