During the MIT course "Napkin to launch", I was part of the only online group who has made and presented a project. Our project was "Ethclassify", an application on the blockchain to share documents in a decentralized way thanks to smart contracts and IPFS.
The design of the application makes it virtually impossible to have a single point of failure.
It uses a smart contract to have an asynchronous and totally secure communication channel to handle the document access requests.
IPFS is used to share any document in its encrypted form and the smart contract is then used to share the key
I am currently working on a scala version of Ethclassify that uses eth-contract-api
you can find the code here