There’s a printable PDF book on the Essence Of Permaculture, a desktop background image on the 12 principles of permaculture, and two printable posters on the ethics and principles of permaculture, and the permaculture flower.
On that site are also a number of permaculture publications for sale – books, magnets, and a 2009 diary and calendar.
I just ordered the calendar to hang on my cubicle wall at work.
Have a good look around the Permaculture Principles site. They also have some great permaculture videos, links to other online permaculture resources, a collaborative permaculture photo log (contribute some of your own photos!) and lots of articles.