Perpera is a document audit protocol loosely based on the PeerAsset protocol and released by the Peercoin Team. It allows for document notarization, document ownership transfers and querying of the revision history. It combines the immutability of a public blockchain and some elements of the git protocol. The web client, which is now released, is a simple to use frontend intended for mainstream use.
You can now easily upload document hashes and share them via the blockchain. It is as simple as attaching a document and signing it with a private key. More updates and features will be coming in the next few months, so stay tuned.