The World Wildlife Fund have released an electronic document format .WWF intended to save paper by not allowing printing.
PDF already has an option to stop documents being printed. It seems likely that WWF is just a modified PDF generator with this option permanently turned on.
.WWF appears to be simply a marketing gimmick, much like the "Blackle" website which claimed to save power by using a black background.
Rather than trying to stop people printing large documents, it would be better to provide tools to help people create smaller electronic documents, which are easier to read on screen and which are archived electronically. These would then not need to be printed and, if printed, would not waste as much paper.
One simple technique is to offer a short summary of a report, before offering the full document. What is commonly done at present is to have the link to the PDF at the top of a web page which announces a report and a summary underneath. The natural reaction of readers is to click on the link and download the full report, without reading further.
If instead the link is at the bottom of the page, the reader has to
scroll down to find it, past the summary. Most readers will not do this and so never find the link. If the full report is not downloaded, it can't be printed and so will not waste paper. A bonus is that this will reduce the load on the web server and the network. It will also reduce storage space on the client computer and thus may reduce materials and energy consumption.
In addition, PDF documents designed for printing are harder to read on screen than web pages designed for online display. There is therefore the temptation to print a PDF document. Providing a short summary document in web format reduces this temptation.