HelpNet Security News has an article today on a new trojan that sort of holds your computer ransom.
This software is distributed as installers for popular software like Divx or uTorrent, and distributed through sites with domain names that look official to those not already familiar with what the real site's name ought to be.
Once you've downloaded and installed it, the program asks you to "unlock" it by sending an SMS text message from your cell phone to what is essentially a 1-900 type service. You send a text message, they send you the "unlock" code, and your cell phone gets billed for the "service".
Fortunately, this version isn't a drastic as some other ransom-ware that actually prevents you from using the computer until you get the unlock code.