There's a free new green-printing software application out from Xerox that works with its ColorQube 9200 series multifunction printers.
The app, called Xerox Print Advisor, works by reminding you, for example, that MAYBE you should print that document on both sides of the paper instead of one. If you are a print manager or office administrator, you can also keep track of who prints what. So, if there's someone abusing the privilege, so to speak, you can speak to that person about adjustin gtheir behavior.
You can extend the application to ALL networked printers in the premium edition which (you knew there was a catch) you'll have to pay for. Actually, you can't get the premium edition until fall 2010, so the pricing is not available yet.