QGIS is a powerful, user friendly, free and Open Source Geographic Information System (GIS). It runs on Windows, Mac OS X, Linux, Unix, and Android and supports numerous vector, raster, and database formats and functionalities.
At L ~ P : Archaeology we exclusively use QGIS for all our GIS requirements and have developed a number of plugins to support archaeological projects and to integrate with ARK. We have released some of these plugins for all archaeologists to benefit from and will release more over time.
Currently these plugins are hosted in our beta testing repository and are marked as experimental, but once stable will be submitted to the main QGIS repository. You are welcome to try out these plugins and to provide feedback, but please be aware that they are in beta and so may still have some bugs.