This open-source chat program purports to be encrypted and with no back doors, and it has Tor built in. It erases the conversation after it's idle for an hour.
The creator of it, a kid from Canada named Nadim Kobeissi, has been detained several times at the US border because the alphabet soups wanted to know what algorithms it used for its encryption. I'm going to add this link to the computer privacy page.
See this article here http://www.activistpost.com/2012/06/anti-surveillance-app-developer.html