Written in C, Tox aims to give you a bit of privacy (at least until the NSA can decrypt all the stored data!). It's been created to be easy to use and let you connect without anyone else listening in.
I'm always a little sceptical about projects like these because I don't know how well the software is written from a cryptographic point of view. I understand a little about how encryption works but am certainly not qualified to judge it. But having source code like this out there to do this is definitely good.
I do think P2P is the way to go for privacy because it's a lot harder to vacuum up than a server based protocol. Perhaps thats why Microsoft switched Skype to server based (from P2p) after they bought it?
- Link permanently added to Cross platform C Code Library