Arc-Team uses Debian to build ArcheOS (Archaeological Operating System). We installed this system on three PCs, seven notebooks and a rugged laptop (for field-work). In this way we can do all the operations we need for computational archaeology (excavation management through GIS, statistical analysis, territorial projects, archaeological drawing, 3D documentation, etc.)
Arc-Team is developing ArcheOS since 2005 and, after some years of experience and three releases based on other distribution (PCLinuxOS 0.92, Kubuntu 7.10, Kubuntu 9.04), we chose Debian stable for the fourth version. Debian assured us the stability we needed and an excellent system for managing internal software.
In other words we use Debian to introduce FLOSS philosophy in archaeology, in order to encourage an open approach to the discipline, with a free exchange of data and ideas. In short, why do we use Debian? Because we want to be free!