Looking instead for a general overview of charting, mapping, and other data viz toolkits? Check out datavisualization.ch.

Installing Open Geo Software from Source is best!

Mac edition • Ubuntu edition

But if you're just getting started...

If you don't have PostGIS or the rest of the open gis stack installed, check out ultimate osx geo install guide by @tokumine. For the Mac, you'll want to download most packages from KingChaos.

See also: Don’t Panic: An Absolute Beginner’s Guide to Building a Map Server - targeting Ubuntu on Rackspace Cloud Server. PostGIS, Mapnik, and TileStache are covered.

GeoDjango has a good Ubuntu step-thru »

Same for PostGIS 2.0 »

• Python 2.6+ (might need to upgrade the default version that ships with Mac OS X)
• PostGIS (a nasty install process, required to give TileStache a shapefile after “importing” it into PostGIS).
• TileStache (has some dependencies)

•   sudo easy_install modestmaps
  

•   sudo easy_install werkzeug
  

• Mapnik (easy Mac installer)

• TileMill - 2nd generation of open source cartography tools from Development Seed. Uses carto css like language to style maps, can host on MapBox.com.

• CartoDB - 2nd generation of open source cartography tools from Vizzuality. Like Google Fusion Tables.

• QGIS - 2nd generation of open source cartography tools. Like ArcMap. They win an award for worst download page ever. Sorry.

• GIS Look for Mac - GISLook and GISMeta are plugins for Mac OS X 10.5 and higher that show GIS data in the Finder and other applications. Including vector data like SHP, e00, adf, BIL, Essi ASCII grid (.asc), binary grid (.fld with .hdr file), PGM, SRTM (.hgt and .dem), Surfer Grid (.grd), and USGS DEM (.dem).

• Postgres.app for Mac - the easiest way to run PostgreSQL and PostGIS on the Mac and supported by Heroku Postgres.

• ArcGIS-OGR plugin - The GDAL/OGR Plugin for ArcMap adds read support to any of the vector formats supported by GDAL/OGR.

• http://www.bostongis.com/pgsql2shp_shp2pgsql_quickguide.bqg