I recently gave a talk at Schumacher College, as part of my Certificate in Education course there, on free and open source software, the Creative Commons, wikis and ending up with Wikipedia. Copyleft licenses like the GPL and Creative Commons share-alike encourage creative people to share their work for use and expansion by others, and the results are sometimes breathtaking (think of the GNU/Linux operating system, for example).
I give all my photos on flickr.com a Creative Commons license that enables people to use them as long as they cite me as the original photographer. Recently I got a surprise email from another flickr user saying he had chosen to use one of my photos in a book he has created.
The book, entitled “ROY G. BIV a convergence of Flickr, Blurb, and the Creative Commons”, explores the colours of the spectrum; my photo is in the violet part ;7 One third of the sales is going to support Amnesty International. This is a project I am proud to have been able to contribute to.