[Tutankamon]

A map to find treasure or secret passwords or the end of the world plans...Just imagine what could end up in the blockchain. Part time capsule part safe part invisible ink part James bond part infinity. Just think of all the craziness..I need to put something in the blockchain. But what...

[cassetti]

https://proofofexistence.com/

[amingilani]

Or my favorite: stamp.io

If you have an Estonian ID, Stamp.io lets you sign it too!

Full disclosure: I know the Stamp.io team, and they're awesome.

[tragomaskhalos]

With terrible Dan Brown book and Tom Hanks film to follow ....