«Tired of spam? reCAPTCHA Mailhide helps you protect your inbox by asking people to solve a reCAPTCHA before they can view your email address.»
A nice, simple, smart and useful tool from the guys at reCAPTCHA: reCAPTCHA Mailhide.
Test it here with my e-mail address: s…@smux.net (click the dots before the @).