Digital Disposable
Ever wanted an email address for just a couple of minutes? Like when a site asks you for your email to send you a password to let you in for no good reason? Well here are a couple of solution:

Jetable.org will generate an email on their domain that will redirect to your real email address for a period of time you set, form 24h to 8 days.

Mailinator.com lets you make up an addresse on the spot. Enter "test@mailinator.com" as your email anywhere and then go to mailinator.com, login with "test" and bingo, you have the mail that was sent to "test@mailinator.com". No passwords or any security, but then again the mail is ereased every couple of hours. Yes, two people can be using the same address at a time and anyone can go in to see any address's mail. The advantage is that you don't have to visit mailinator.com before using it, an account is automatically created when the mail is received and can then be accessed. Also the site has a good sense of humor (check the FAQ).

The cost you ask? Free. Isn't this great?
Source: evhead.com