You probably won't be aware, but this website is set up as a 'Honeypot'. Spammers troll the web looking for email addresses to spam, so hidden on this site are links to email addresses set up purely so that spammers (with automated scripts) will find them, and non spammers won't. The email addresses are not used for any other purpose, so when the spammers use them this information is registered. The Honeypot project knows which email addresses appeared where, and this information is of use in tracking the behaviour of spammers.
This morning I caught another one, the spammer is sitting in Romania.
Nice to know that the five minutes it took to set this up are having a payoff.