Ask HN: options for international health insurance?

I'm currently US based, but the wife and I are looking at trying to be more flexible in our location -- splitting time between Germany and the States.

Being a German national and having kept her personal insurance, she's already fine for moving around. For myself, born/raised in California, it is more interesting. I currently have insurance through my employer, but am wanting to look into a long term personal health insurance policy that can handle an international lifestyle.

We checked with my wife's German insurer, but they have a requirement of local residency which makes sense.

Are there any recommendations for options? In short, I am looking for a personal insurance policy that isn't insanely expensive and works as readily in the states as it does in europe.