One interesting application is the ability prove that something existed at a specific point in time (at scale). Publish the hash of the content to the chain. T

One interesting application is the ability prove that something existed at a specific point in time (at scale). Publish the hash of the content to the chain. This can be scaled by combining an arbitrary number of items into the same hash using a merkel tree (https://petertodd.org/2016/opentimestamps-announcement#how-opentimestamps-works https://petertodd.org/2016/opentimestamps-announcement#how-o...). It's not a new idea - you could also publish the hash in a bunch of newspapers, but it's not as easily scalable, still relies somewhat on a third party, and the cost of independent verification is much higher. How useful it actually is and if it's worth the cost is another question.