See Misty Portal.

I'd just like to say that this text cut off for me at the word flip.

So yeah. If non-combat damage happens? Flip. Not flip any specific thing; you just need to flip out.

I approve.

But these do seem like a very limited use-case to me. Compared to "Be a 1/1 creature and not be dead" as a condition for being mana, it feels like a lot of hoops to jump through.

That's a perfectly fair argument. The genesis questions here were "What if a land could be cast?," and "Can a make a balanced mana rock the costs in today's economy?"

I arrived at these because -cost artifacts aren't currently allowed to produce or a colored mana. I agree that the hoop-jumping isn't exactly an elegant solution.