Spam... never open it, a single linked image can confirm you exist when it's downloaded. NEVER unsubscribe.
Curiously I was getting 150 messages a day, I just couldn't care less, it just gets sorted by Outlook. That's now down to about 10. And I've don't nothing... so I can only conclude that efforts being made to put offenders in jail must be working. There have been some pretty high profile cases in the US.
These dudes are arguably the leaders in spam prevention
http://www.spamhaus.org/
"Spamhaus tracks the Internet's Spammers, Spam Gangs
and Spam Services, provides dependable realtime anti-spam protection
for Internet networks, and works with Law Enforcement to identify and
pursue spammers worldwide."
And here's a picture for a recent assignment. ;)