On Jeffrey Zeldman‘s site I found a link to Enkoder 6.0, a very usefull and free anti-spam email address encoder created by Hivelogic.

Posting your email address on your web-site is a sure-fire way to get an Inbox full of spam. One way to protect yourself is to “encode” your address, making it more difficult to discover.
The Enkoder Form will encrypt your Email address and convert the result to a self evaluating JavaScript, hiding it from Email-harvesting robots which crawl the web looking for exposed addresses. Your address will be displayed correctly by web-browsers, but will be virtually indecipherable to Email harvesting robots.