wp-spamspan Protects WordPress Blogs Against Spam Harvesters
Nearly two years ago, I published wp-spamspan in my Software Archive. Good things come to those who wait: I finally published it in the public WordPress Plugins Directory: http://wordpress.org/extend/plugins/wp-spamspan/
This plugin allows you to post email addresses (such as chip [at] unicom [dot] com) on your WordPress blog. The plugin filters the display text and automatically munges email addresses to something like:
chip [at] example [dot] com
Then, when loaded into a web browser, a dynamic script scans the page and converts the munged email addresses back to clickable links.
My experience has been that the protection is very good, and the plugin has been reliable.
By the way, I didn't invent spamspan. I just adapted it to WordPress. You can read more about it here: http://www.spamspan.com/