Platform: BlackBerry 

The infamous BlackBerry app makes it easier to separate your standard address book from the private one by maintaining a list of hidden contacts. Since no icon is present on the home screen, owners are required to punch in a custom-launch code on the QWERTY to gain access. There's also an option to customize the alert display to read “system memory low” when a mistress reaches out at the worst possible time.

Click here to Download it Now from BlackBerry World, $2