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.
The goal of the CGAL Open Source Project is to provide easy access to efficient and reliable geometric algorithms in the form of a C++ library. CGAL is used in various areas needing geometric computation, such as: computer graphics, scientific visualization, computer aided design and modeling, geographic information systems, molecular biology, medical imaging, robotics and motion planning, mesh generation, numerical methods... More on the projects using CGAL web page.
matplotlib is a python 2D plotting library which produces publication quality figures in a variety of hardcopy formats and interactive environments across platforms. matplotlib can be used in python scripts, the python and ipython shell (ala matlab or mathematica), web application servers, and six graphical user interface toolkits. matplotlib tries to make easy things easy and hard things possible. You can generate plots, histograms, power spectra, bar charts, errorcharts, scatterplots, etc, with just a few lines of code.