I've always wanted a good interactive map that shows terrain altitude in the sort of color gradient manner that most of Windy's map data are represented in. It seems to me the engine is perfectly suited for it, and would be a simple of matter of say inputting ASTER GDEM data, or the like. I'd appreciate it if this were implemented. I also think it would be a useful visualization for a number of activities.
Really love the site, by the way. Well done!