Hide Your Email Address from Third Party Facebook Apps

Many Facebook Apps (like Farmville) need permission to send you email before you use them, but many of you might not want to share your email for privacy reasons. If you'd like to keep your email private, you can actually have Facebook create a temporary forwarding email just for apps.
When you first get the permissions prompt from an app (shown above), just click the "Change" link under "Send me email", and Facebook will create an anonymous email address for you. Messages from that app will be forwarded to your main email address, but the app will never see your actual email—just the anonymous one Facebook created.