Lavasoft has published an image gallery, displaying screenshots of fake anti-virus software.
Rogue anti-virus software is a very common threat on the internet. It is essentially malware that poses as security software. In most cases its motive is to blackmail victims into paying for virus protection (which will be of dubious quality, at best). In reality, these programs are scams designed to con credit card details from worried people.
A while back I have created a short video that demonstrates a fake AV program in action.