Mapnik is a Free Toolkit for developing mapping applications.
It's written in C++. It can comfortably be used for both desktop
and web development, which was something I wanted from the beginning.

Mapnik is about making beautiful maps. It uses the AGG library
and offers world class anti-aliasing rendering with subpixel
accuracy for geographic data. It is written from scratch in
modern C++ and doesn't suffer from design decisions made a decade
ago. When it comes to handling common software tasks such as memory
management, filesystem access, regular expressions, parsing and so
on, Mapnik doesn't re-invent the wheel, but utilises best of breed
industry standard libraries from boost.org