Mermaid for message sequence diagrams is amazing -- we recently added 'GPT for diagramming' support to Louie (conversational data & compute notebooks), and combining these rich DSLs with conversational AI & an interactive UI is a pretty cool & time-saving experience because it can bootstrap a lot
Example from work where the original took 1-2 hours: https://www.loom.com/share/aa388d49f28d471d89e3d8c048e9c0a0
It's amazing to think where these will be even 6mo from now