MailDrop - maildrop is a Mail delivery agent used by the Courier Mail Server. The maildrop MDA also includes filtering functionality. maildrop receives mail via stdin and delivers in both Maildir and mbox formats.
Guerrilla Mail - Guerrilla Mail is a web-based app that provides a disposable and anonymous email address. Users of the service are not required to set up an account in order to send or receive emails.
10 Minute Mail - Temporary disposable e-mail service to beat spam. Avoid spam with a free secure e-mail address.
TrashMail.com - Create a free disposable email address! Its really easy to use:
Mailinator - Any Inbox. Any Time.
AnonAddy - Create unlimited aliases for free. Protect your email from spam using disposable addresses. Encrypt forwarded emails with PGP encryption using this service.