SpamMotel is a great free email forwarding service that generates random email addresses for you to give to untrusted sites on the net. You dispose of these addresses easily if spam ever starts flowing. The site is:
http://www.spammotel.com [BrokenLink]
SpamMotel creates dummy addresses for you that forward to a real address with a brief message saying which address the message was sent to. You give the dummy address out to a site such as SixDegrees? and if you start receiving spam on that address you simply turn it off. It's also a good way to discover if signing up at various sites gets your name onto spam lists because you can always tell where the spammers got that particular address. -- BrianRobinson
See SpamDefenseRoadmap for similar services.