Do you mean blockchain or technology inspired by blockchain? Lots of cool merkle tree stuff (trillion, certificate transparency); also several international shipping supply chains use blockchain for chain-of-custody (txns are irrevocable cosigned transfer of custody with no trusted overseer). I would love to see criminal evidence and deeds of ownership move onto a similar framework.

I expect digital ID will also benifit from an auditable, immutable log (e.g. sovrin)