Here's some stuff on zerocash:

Zerocash: Decentralized anonymous payments from Bitcoin: http://diyhpl.us/~bryan/papers2/bitcoin/Zerocash:%20Decentra...

Zerocoin: anonymous, distributed e-cash from bitcoin: http://diyhpl.us/~bryan/papers2/bitcoin/Zerocoin:%20anonymou...

How to explain zero knowledge protocols to other people's children: http://diyhpl.us/~bryan/papers2/bitcoin/snarks/How%20to%20ex...

GGPR paper, NIZKs without PCPs: http://diyhpl.us/~bryan/papers2/bitcoin/snarks/Quadratic%20s...

Snarks for C: Verifying program execution succinctly and in zero knowledge: http://diyhpl.us/~bryan/papers2/bitcoin/snarks/SNARKs%20for%...

Secure sampling of public parameters for succinct zero knowledge proofs: http://diyhpl.us/~bryan/papers2/bitcoin/snarks/Secure%20samp...

https://github.com/scipr-lab/libsnark

FWIW I think that confidential transactions and even SNARKs will eventually make their way into Bitcoin.