We discovered a cool software toy in Dave Shaw's class this week. It's called Cain and you can download it from OXID (www.oxid.it).
It's a scanner/hacking tool/security tool. Very interesting. It's got a sniffer, ARP-spoofer, plus some interesting tools for hacking (spoofing DNS), etc. It's a toy that will be fun to play with more. And great for demonstrating in class.