Bleep has been out as a pre-release alpha version for nearly a year now, but with the public launch, you can now chat from Windows, OS X, iOS and Android. It works much like any other chat app you've ever used, but with added privacy: using the 'Whisper' function, messages are only stored locally, and deleted from every device after 25 seconds. There's even in-built screenshot protection, which guards against nicknames or text being captured.
Although it certainly doesn't have the ubiquity factor going for it, Bleep looks like a robust technological method to fight back against government surveillance — although let's be honest, the NSA is probably still rifling through your crap, one way or another. [Bleep]