Mac OS X installers for QGIS. For OS X Snow Leopard, Lion & Mt Lion.
See the QGIS website for more information about, and help with, QGIS.
QGIS now includes its own copy of GRASS, so no external GRASS is needed. Internal copies of Orfeo Toolbox, SAGA and TauDEM are also included.
Dakota Cartography provides nightly development builds.