A Visual History of Spam
Cristiano writes "Microsoft employee Raymond Chen has saved every spam message and virus-laden e-mail he's received at work since 1997 and graphed the spams and viruses to create a cool visual representation of one man's malicious traffic."
An interesting aside: Raymon Chen is mentioned in the Linux kernel's source 'CREDITS' file:
N: Raymond Chen
E: raymondc@microsoft.com
D: Author of Configure script
S: 14509 NE 39th Street #1096
S: Bellevue, Washington 98007
S: USA
One of several talks of his on spam (complete with more graphs): http://www.linuxchile.cl/docs.php?op=verVersion&do c=64&id=1
And he's even done generated some really really horribly insane spam collages, but I'll let those interested dig around for them on their own.