MIT's Enigma
Currently, the project is developing its private beta and is promising to launch soon.
From the official website: Enigma is a decentralized cloud platform with guaranteed privacy. Private data is stored, shared and analyzed without ever being fully revealed to any party. Secure multi-party computation, empowered by the blockchain, is the magical technology behind it.
Article in the Wired.
Whitepaper: "Enigma: Decentralized Computation Platform with Guaranteed Privacy";
Reditt dicussion on Whitepaper, including some comments by Buterin;