This reminds me of Coinbase in the early days-- a beautifully designed, easy to use product that enables a new application of the blockchain: proof of ownership.
It remains to be seen what the killer use case will be to a product like this, but imagine a designer proving ownership of digital work so it can't be copied, a music producer proving ownership or a new beat so it can't be copied, or a VC proving ownership of a term sheet.
I am bias, Bitproof is a part of Boost VC Tribe 5, but this is a great user interface for certifying things in the blockchain. Super exciting innovation.
Coinbase
Boost VC
GrowthHackers
VacationRenter