The Santa Fe Institute has absolutely enormous windows researchers can write on, complete with markers and erasers. It's surprisingly useful, because they're far larger than any blackboard or whiteboard.
I feel like this is becoming standard in lots of places, or at least vogue. I worked in a chem lab at the University of Washington that had indoor windows expressly for notes and presentations, and the science library at my school has rooms with glass walls and markers for group studying.
