"TinyMailto.com let you convert your e-mail address into an URL that is protected from spammers by a captcha test.
You can use a tinymailto URL to put it in public places, like web pages, forum/e-mail signatures, etc. If someone wants to get your e-mail address, the person must pass a Captcha test in order to view and use your e-mail address.
This way, you can protect your e-mail address from spammers and web robots (web-bots). "
More info at tinymailto.com