Flour

Flour in Germany is classified using flour type numbers which of course isn't available in the US. I consulted multiple websites (including the Wikipedia page above) that try to translate the type numbers into the kind of flour you can buy in the US and eventually settled on this:

Wheat flour 

• Type 550 - All purpose flour
• Type 812 - Bread flour
• Type 1050 - Medium stone ground wheat flour; previously used Graham wheat flour and sometimes just go for bread flour if the other flours used in the recipe are mainly whole grain
• Whole grain - Whole grain wheat flour
• Hartweizengrieß - Durum wheat semolina

Rye flour

• Type 815 - Light rye flour, I use Bob's Red Mill Light Rye
• Whole grain - Whole grain rye flour

Spelt flour

• Type 630 - White spelt flour
• Whole grain - Whole grain spelt flour

This still doesn't give me the full range of flour used in the recipes, in fact I haven't found a replacement for the most widely used rye type 1150, but by being slightly creative it has worked out quite well so far.

For those of you living in San Francisco, I buy most of my flour at Rainbow Supermarket. They have quite a wide selection and you can buy in bulk, so you can choose how much ever you need.