Have you ever thought about advertising on textbooks? Textbooks are widely circulated, and the readership is well targeted; then, why not? This website is doing exactly this. Now you can download a wide variety of textbooks (and travel guides and business titles) for free - even without registration. These textbooks are written for this website and only available here. I'm not sure how many professors will begin using such free texts for their teaching (and I do hope my professors will), but this could be an alternative future of the over-profiting textbook market we are facing now.