You could also send some emails out to the makers of some anti-virus and malware...

You could also send some emails out to the makers of some anti-virus and malware software (McAfee, Kapersky, LavaSoft, etc.); I'm sure they have plenty of samples they could offer you.

Also, check out this list of big computer worms on Wikipedia, perhaps you could search around and find copies of them: http://en.wikipedia.org/wiki/Timeline_of_notable_computer_vi...