MintEmail.com 
Posted on January 03, 2008
A four hour temporary email address
MintEmail.com gives you a four hour temporary email address. Your new temporary email address has been already saved to your clipboard (no need to press Ctrl+C). All incoming emails will be displayed on this page.
Email Forwarding also available: Do you need a temporary email address longer than four hours? If so, then you can create a mintemail.com email address that will forward all emails to your real email address.
Appify July 25, 2008
A similar, and in my opinion better, temporary email service is GuerrillaMail.com. It checks mail quicker, and has richer features. Check out my review of it here:
http://appify.blogspot.com/2008/07/guerrilla-mail_21.html