GNOME is a simple, powerful desktop environment for GNU/Linux. It is used for office workstations, kiosks, POS systems, and more.
GNOME is used in deployments ranging from one to tens of thousands of users. The City of Largo, Florida uses thin-clients to serve hundreds of staff on the cheap. Peugeot Citroën is deploying 20,000 GNOME desktops.
The GNOME Desktop Administration Guide is the primary resource.