ImageNetBarrier X5 is a very powerful way to protect your Mac while it’s connected to the internet. Some of the most interesting features are:

  • Blocks hacker and vandal attacks
  • Blocks ads from websites
  • alerting you of any application that tries to create a network connection, or “phone home”
  • filters all outgoing data to ensure that no sensitive information leaves your computer
  • see your network traffic in real time

The interface is nice and straight-forward. The purchase page is a bit overwhelming, but as far as I can tell it is $50 for a one seat license. You can find out more on the developer’s website.