PPR is a spooler for PostScript printers. It supports PPD files, and provides operator alerts, job result messages, and error recovery. It is integrated with Netatalk, CAP60, Samba, and Ghostscript. It has command line and web interfaces.
ChemVisio is software which might be useful for educational purposes (non-organic chemistry, crystallography etc.). It might be a good visualization support for all people who need better illustrations than that you could see in books.