The Minecraft Overviewer
The Minecraft Overviewer is a command-line tool for rendering high-resolution maps of Minecraft worlds. It generates a set of static html and image files and uses the Google Maps API to display a nice interactive map.
The Overviewer has been in active development for over a year and has many features, including day and night lighting, cave rendering, mineral overlays, and many plugins for even more features! It is written mostly in Python with critical sections in C as an extension module.