The Safe Mac ▸ Ongoing MacKeeper fraud:

"Controversy about MacKeeper has been around almost as long as MacKeeper has existed. It is one of the most aggressively-marketed products in the Mac world, and there are numerous accusations that it isn’t useful or even that it is fraudulent. At the same time, you will find a number of positive reviews out there. How do you know what’s true? In this article, I will make the case that MacKeeper, and the company behind it (ZeoBIT/Kromtech), are not to be trusted."

This app was breaking Acorn's signature for a while, causing it to stop launching on customer's computers. It does evil things, and I don't know why Apple hasn't pulled their cert yet.