PaperCut NG: A Printing Quota Management Software

PaperCut NG™ is a print and internet quota, charging, tracking and monitoring system designed to promote the responsible use of IT resources. It's a premium cross-platform solution specifically designed to meet the needs of schools, universities and other organizations. Implementations range from silent monitoring, quota control to user-pays systems.

http://www.papercut.com/products/ng/