A visit to the dark side of the internet will find you looking at Malware that the antivirus co's are still to discover..
Some of the items found on these site only show on the AV sites many months after their release... these Bots have been around for several years.. they are nothing new.. And with Organised Crime now financing malware coders.. yep they're now getting better written..

As for the AV co's writting the stuff or bankrolling the coders.. No .. well not anymore.. there were strong suspicions that KAV , Norton and McAfee did in the early days.. but not now.. even the hint of that sort of activity would have their stocks frozen..

do a hunt on a old skrit-kiddie toy like Optix or Beast.. you will find sites that talk about malware and their activities will curl your toes.. the AV coes are not even close to having all their bases covered..

Cheers