in addition to towny's advice on avoiding spam..
if you own a domain and can set up a few email forwards for it, then you can set up addresses that allow you to pinpoint where the spammer has harvested your address.. eg: my email for this site is: nthellworld@*domain* so i know that anything sent to that address has been found by looking at this site.
i also set up an address where i sign up to things that i know would never send me anything i want which i name: spam@*domain*.
all this setting up is worthwhile when you set inbox rules on your email client.. you can automatically delete anything that comes in for the spam@ address... or forward the nthellworld@ ones to a folder called "nthellworld"... you get the idea.
also, for website authors.. there are lots of useful javascript solutions to making your address invisible to automated bots that harvest addresses if anyone is interested in those i can send you details.
lastly, the most common tactic is to shove the words no spam into a valid address with the assumption that whoever uses it has the sense to remove the added text before using it.. eg: nthellworld@*domain* becomes nthellworldNOSPAM@*domain*
hope those help someone out there
*edit: sorry dooby .. didn't mean to repeat what you've put.. it took me a while to write it all out, yours wasn't there when i started me=
/edit*