Spam Gourmet is a clever little service which lets you sign up for disposable email addresses to use with online logins, shops and the like. You give out the Spam Gourmet address, and it will forward messages coming into that address to your private email address.
The really neat thing is that you can specify just how many emails you want to receive (max 20) before the address self-destructs, which makes it great for signing up for newsletters or something where you know you’re going to receive more than one message. It’s an elegant, free and very flexible service.