a Free C++/Python GIS Toolkit for developing mapping applications. Above all Mapnik is about making beautiful maps. It is easily extensible and suitable for both desktop and web development.
GDAL - Geospatial Data Abstraction Library Select language: [English][Russian][Portuguese][French/Francais] GDAL is a translator library for raster geospatial data formats that is released under an X/MIT style Open Source license by the Open Source Geospatial Foundation. As a library, it presents a single abstract data model to the calling application for all supported formats. It also comes with a variety of useful commandline utilities for data translation and processing. The NEWS page describes the November 2009 GDAL/OGR 1.6.3 release.
Delny is a Python package which can be used to make a Delaunay triangulation from a set of n-dimensional points. It is effectively a Python interface to libqhull, the C library of the Qhull program, but (currently) restricted to Delaunay triangulation. It was first developed to use in a mesh generator developed as dissertation at the University of Southampton with Hans Fangohr as supervisor. This very specific application area was the reason for the limited functionality of the libqhull wrapper, which in turn is likely the reason that there is useable code available.
geopy makes it easy for developers to locate the coordinates of addresses, cities, countries, and landmarks across the globe using third-party geocoders and other sources of data, such as wikis.