The latest breed of malware threatens to blackmail you by telling the world+dog about all the porn sites you visit. If you are dumb enough to pay, the software just sends all your credit card details to Russian criminals who use it to empty your bank-accounts.
The Kenzero Trojan, which has been seen in Japan, demands $18 to remove the personal details of your browsing history from its blackmail site. It gets on to your PC by pretending to be a game registration window which then takes your personal details then attempts to extort money out of you.
Kenzero has been spreading by the Winny file-sharing network, which has approximately 200 million users. The idea is that the software that hid the malware was illegal in the first place, so you are hardly going to complain.