jmLÑMemo is awesome. I think all of these message systems should. Connect. This one is powered by doge and is quite different and can be understood and interacted with from outside the system: https://dime.cash
https://whatsonchain.com/tx/92ee9bd542922169f045f85355867b892c3d44fd7bff52b3b8a0b0e8af25af09