How do you present your e-mail address to the website visitors without making it also available to programs that scan websites to harvest them?

Construct it using JavaScript! While security through obfuscation is not a good general practice, it works in this case because the program is looking at many, many sites and is scanning for keywords and patterns.

<!--
var name = "RiBiNiN";
var atsign = "@";
var virtual_domain = "RiBiNiNDesigns";
var dotcom = ".com";
document.write("<a href=mail","to:", name + atsign + virtual_domain + dotcom, ">", name + atsign + virtual_domain + dotcom, "</a>");
// -->

Be sure to use your own variable names and even use different break points between and inside words.