Mailinator.com is a great way to deal with annoying site registraion, or if you ever need disposable/temporary email addresses. You don't need to set-up or sign-up with Mailinator. Suppose you are on a registration form for Xyz.com. In the email address field, just make up any old address at mailinator.com, like rtuuug@mailinator.com. Then to get the email, go to Mailinator.com and enter rtuuug (the thing you made up). There's no passwords, and there is no sign-up.
Of course, you don't want to use this for email that will contain sensitive data. As their FAQ says:
Q: This sounds pretty insecure. What if I send important emails with sensitive super-secret information in them to mailinator?
A: Then you are a stupid-head. That isn't what this is for.
They even have an RSS feed for each made-up account, so you can almost use this as a "real" email if you don't have any privacy/security concerns. You'd use the RSS to get notified when new email arrives.
I first discovered this a few years ago. Looks like there are now others doing the doing the same thing, like myTrashMail.com