Printbill 4.2.0

Printbill is a sophistocated Unix print billing and/or accounting system with associated administration utilities. It primarily supports LPRng but now has limited CUPS support as well.
A simple print filter and accompanying daemon perform pre-printing billing, post-printing billing, print-accounting and print job quote generation. In addition, various utilities for administrators and users are provided - including programs to check your print quota and usage patterns, a web interface for both users and administrators and a command-line quote generator.
Charge rates may be specified on per-page, per-percent-coverage or both, and any number of printers/print queues can be provided (with different charge rates and printer parameters). Monochrome and CMYK colour printers are supported (with separate charge rates for both colour and black ink).
For all filters, processing can happen out-of-order, and you may prioritise jobs on the basis of size (jobs larger than a threshold can get lower priority or higher priority as desired) and jobs are billed in parallel / overlapping - jobs which finish billing first get printed first.
This is not necessarily the same as the order of arrival. Detailed stats are collected on a per-printer basis for job size, CPU time for each job, page count and ink/toner coverage, so you can analyse the usage patterns for your printers and predict when a cartridge will need to be replaced. It supports an optional user-supplied anything-to-postscript filter, so you can get properly billed for plain text, DVI files, image files, and so forth as well as PostScript.
Databases and configuration files may be stored on a centralised web server. This allows read-only access so that Unix (and conceivably Windows) clients could easily check quota, calculate quotes etc. remotely.
For fun, an additional filter is provided which allows users to deduct fixed amounts from their accounts (we use it to let students buy drinks and food from an unsecured laboratory fridge).
Enhancements:
- Finished support for per-user per-printer stats, tested that it works.