Streets GL is a web-based 3D map that uses OpenStreetMap data to render features such as buildings, roads, paths, trees, etc. on top of a dynamic terrain. Geometry for tiles is generated in runtime.
Source code is available on GitHub: https://github.com/strandedkitty/streets-gl
Wow, this looks really good. The buildings rendered in 3d look a lot better than Google Earth models, especially around central London, I guess OpenStreetMap data is pretty accurate for geometry.