One other thing I had wondered about was the Safari business model. I had assumed that there was enough reference material freely available online for most things that Safari wouldn’t provide a significant marginal benefit. As I wade into the PHP world, though, I find that the online reference material is generally lacking. The PHP manual is pretty uneven, and most of the developer resource sites run by third parties are advertising-laden crapfests. Safari really hits the sweet spot there. I wonder how many subscribers they have? Any money they do make must be almost pure profit since O’Reilly already owns the rights to the books and the site must not be horribly difficult to maintain.