Mailinator (Score 2, Informative)

Whenever a site asks me to register before I can access content (and I don't mind my username/password being made public), I use http://www.mailinator.com/. You basically [e-mail], and then head over to the site, type in your made up email address, and it shows you the last 5 (probably spam) messages it has received. Of course its totally unsecure (but that's sort of the point), so be careful what you use it for.