If you ever want to really scare your wireless (WiFi) users, download a Macintosh software package called EtherPeg. EtherPeg will let you put your WiFi card into “promiscuous” mode and it will quietly listen to all of the unencrypted wireless traffic and then display any JPEG or GIF files that it intercepts. This is a fascinating program and a good shocker to show users how insecure unencrypted wireless networks are. It doesn’t display anything that is done over encrypted WiFi or through encrypted browser connections.

I’m not sure if there is a Windows equivalent of this, but I would imagine there is.

–Pete