A final roundup of Macintosh GIS progams that I missed in my original post (they’ll be added to that main listing shortly)
KyngChaos – Mentioned by several commenters; a source of Mac OS X builds of GIS-related software like GDAL/OGR and MapServer.
OSSIM provides advanced geo-spatial image processing for remote sensing, photogrammetry, and Geographic Information Systems. Backed by an active open source software development community, OSSIM solutions have been deployed on a number of critical commercial and government systems.
And going back to my listing of aerial/satellite imagery programs, which included OSSIM:
HEG – “… a tool developed to allow a user to reformat, re-project and perform stitching/mosaicing and subsetting operations on HDF-EOS objects. The output GeoTIFF file is ingestible into commonly used GIS applications. HEG will also write to HDF-EOS Grid & SWATH formats (i.e for Subsetting purposes) and native (or raw) binary. HEG presently works with MODIS (AQUA and TERRA), ASTER, MISR, AIRS, and AMSR-E HDF-EOS data sets.”
Comments and emails also referenced paid Mac GIS-related software:
Avenza – Add-ons like MAPublisher and Geographic Imager for Photoshop and Illustrator
Ortelius – Mapmaking software (coming soon).
TNTMips – Full version of the freeware TNTlite.