I am just after reading about an online virus generator here.
I haven't had a chance to check out the generator cause the settings on the network I'm on won't allow it. I'd be guessing that the virus it creates is relatively simple and easily discovered by any antivirus software but from what I've read I think it could wreak havoc on the machines of casual users who wouldn't have any protection against it (because they don't know better and don't listen to advice). Any idiot that somebody pisses off could now very very easily send viruses left, right and centre which would result in general chaos (maybe).
Oh well I might have alot more work to keep me occupied in the not too distant future.