A cool little deck I did for the MoCo Drupal Meetup in Spring 2013. It mostly has some good examples and shows some of the open source toolkits that make Tilemill tick.
master framework that reads all the various GIS file formats and performs manipulations, all subsequent frameworks are dependencies of GDAL • GEOS (Geometry Engine Open Source) - a unix framework that does map math calculation. It’s super powerful and complex. • NumPY - overrides an out-of-date Python library in OSX (in 10.6 / 10.7) • ProJ - I have no idea, probably has something to do with these .prj files you need • SQLite3 - give GDAL serverless SQLite DB capabilities • UnixImageIO - allows multiple image formats to be interpreted by GDAL GSL (GNU Scientific Library) - provides C/C++ math libraries essential for open-source mapping utilities to work QGIS (Quantum Geographic Information System): a full-fledged GIS program where you can manipulate raster layers, vectors and everything else you need to do a proper map projection. Tilemill: a map tile creating program. It basically creates the zoomable sets of tiles you see with interactive maps online. It will take properly formatted raster and vector files from any GIS software package (like ArcGIS or QGIS) and place them into layers. From here, you can rearrange the layers, and even style the vector layers of your map using the Carto CSS/SASS-