As do those random other sites with cute little 'forward this to a friend!' links.
Well, yeah, but you don't actually read or send those...do you?
I ignore all chain-letter-esque emails completetely, even ones from my dearest family members. If they want to write me, write me. Don't send me that crap.
...But that's just personal preference.
The only way to truly prevent spam is to not use email at all. :-/
Yeah but, like me, you can reduce it enough so that it becomes a non-issue.