bcrowell writes "The NYTimes has an editorial plugging Flat World Knowledge, a startup that will offer college textbooks inexpensively (~$30) in print, and free as PDFs. They plan to make their profits from add-ons like podcast study guides and mobile phone flashcards. Books will be licensed under CC Attribution-Noncommercial-Share Alike. Mashups and customizations are encouraged, but the NC license is incompatible with strong copyleft licenses such as the GFDL used by Wikipedia. Other companies trying to find a workable business model for free textbooks include Ink Textbooks (revenue from online homework) and Freeload Press (revenue from ads inside the books). So far, none of these companies seems to have succeeded in building up much of a catalog of books; it seems more common for authors of free textbooks to take a DIY approach, putting PDFs on their own web pages, and sometimes arranging on-demand printing with vanity-press publishers like lulu.com. Lots and lots of web sites exist to help people find free textbooks, and CalPIRG has an active campaign pushing for affordable textbooks."