In your HTML code, write your e-mail addresses as follows:

<code lang="html"><span class="encoded-email">me [at] mydomain [dot] com</a></code>

Here's the JavaScript:

<code lang="javascript">function decodeEmails () {
	if (document.getElementsByTagName) {
		var spans = document.getElementsByTagName("span");
		
		for (var n = 0; n < spans.length; n++) {
			if (spans[n].className == "encoded-email") {
				var email = spans[n].firstChild.nodeValue.replace(" [at] ", "@");
				email = email.replace(" [dot] ", ".");
				
				var hyperlink = document.createElement("a");
				var linkText = document.createTextNode(email);
				hyperlink.href = "mailto:" + email;
				hyperlink.title = "Send me an e-mail";
				hyperlink.appendChild(linkText);
				
				spans[n].replaceChild(hyperlink, spans[n].firstChild);
				
				linkText = null;
				hyperlink = null;
			}
		}
	}
}</code>

Just call the decodeEmails() function using your favorite window load event handler.