New web services are launched almost every hour that require you to register with a valid email address before you can play with the service. Same goes with discussion boards and internet forums - they will ask your email before letting you in.
And each time you share your personal email address with a not-so-popular website, you run the risk of getting more spam.
Then came disposable email address services like SpamBox or Mailexpire, that let you create temporary email address which expire after a given time. These service forward all mails to your primary email inbox until the temporary email account expires.
A more useful player in the game is 10MinuteMail.com which actually provides a disposable email account and not just a use-n-throw email address.
With 10 Minute Mail, you get a temporary e-mail address. Any e-mails sent to this disposable address will show up automatically on the temporary web page that's visible only to you.
You can read new emails send to the disposable address and even reply to the messages using your new address. Read message are indicated with a tick. And everything expires after 10 minutes or more.
This is much safer since you no longer have to share your personal email with anyone, not even the disposable email service.
10 Minute Mail Address [Thanks Michele]
Related Trick: Get Multiple GMail Addresses with the + Symbol