Most of the examples of data embedded in the blockchain are catalogued here: https://cirosantilli.com/cool-data-embedded-in-the-bitcoin-blockchain
This 2018 paper goes over different techniques to embed arbitrary data, including the Satoshi uploader I'd mentioned:
https://fc18.ifca.ai/preproceedings/6.pdf
@BitMEX
did an amazing article on the OP_RETURN wars that covers Counterparty: https://blog.bitmex.com/dapps-or-only-bitcoin-transactions-the-2014-debate/
The PSBT dutch auction stuff that @orenyomtov
is working on is here https://openordex.org
The case of the Slovakian politician sending financial transactions that were secretly coded messages is here:
https://en.wikipedia.org/wiki/Marian_Kotleba#%E2%82%AC1,488_cheques_court_case
...and I think that's all? DM me if you have any questions and see you next time!
