There may exist a potential Bitcoin rival, fairCash. The founder mentioned this briefly at the Mobile World Congress in a Q&A session with Google. There a little resources on the internet about fairCash and their homepage is written in an advertising tone and the technical information given is superficial:
"It comprises a comprehensive technology framework that combined eWallet hardware and algorithmic software elements to conduct pre-paid eCash transactions which mimic the behavior of Physical Cash in the closest possible way through teleportation of financial objects."
They post a thesis and and patent on their website. Google Scholar finds one "scientific" paper or conference abstract of questionable quality. From these, we can learn, that fairCash tokens are electronic secrets (read some data), issued and cleared by a central authority. They can be circulated using special devices (eWallets) in a peer-to-peer fashion. However, protection against double spending and fraud is only guaranteed by the central authority (and trust into the tamper resistance of eWallet devices).
Can anyone expand?