I started noticing e-mail being sent to strange account names on my mail server recently. I remembered just today that I added some script to one of my web sites that takes the client IP address and the date and encodes it into a text name, then adds the domain name and places it in the home page as a mailto: link. I can then decode the values later.
Today a spam was sent to an account that indicates 18.104.22.168 harvested this address on 6/2/2006. I checked my server logs to confirm this, and sure enough, there it was.
2006-06-02 10:32:06 22.214.171.124 - 80 GET /robots.txt - 200 0 psycheclone -
2006-06-02 10:32:06 126.96.36.199 - 80 GET /index.html - 200 0 psycheclone -
I searched for "pyscheclone" and found this thread. I am assuming this is some sort of high speed web-bot that can be configured for email harvesting.