Squat Captcha - The worst captcha ever! Forces you to do 10 squats
Mailinator - Any Inbox. Any Time.
reCAPTCHA - reCAPTCHA is a free security service that protects your websites from spam and abuse.
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.
Graboxy maze CAPTCHA - Replace fire hydrants and traffic lights with your brand.
Fake Mail Generator - Fake Mail Generator is the provider of free and temporary email addresses that you can use just like original one.