If you can't start the applet in your browser or you don't want the graphical stuff, you can execute a cmdline-version like this:

Download this: pnpeer.jar

Then type at the directory where you have downloaded the jar-file:

java -cp pnpeer.jar pnpeer.pnpeerappl

Remember: Have some Java installed before that (http://java.sun.com)

Valid commands are:

getnear (radius)	# get all Peers in Radius r
msg (peerid) (msg)	# send a message to peer x 
			# (id=0 - broadcast to all peers)
quit 			# leave client