You may know about Mailinator, and how it will hold any email sent to anything-you-want@mailinator.com for a few hours -- great for throw away registrations!
Using Mail.app's RSS reader, you can make Mailinator even more useful by having Mail.app monitor the RSS feed for the Mailinator inbox name you invent. In that way, you don't have to remember to go check periodically for new mail. It's always there!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090409122953143