While writing a book on parallel programming in 1993, I saw an early demonstration of Mosaic, and immediately realized that the book should be published online. After some inspired hacking of latex2html by my colleague Brian Toonen, "Designing and Building Parallel Programs" (DBPP) was published simultaneously by Addison-Wesley and at www.mcs.anl.gov/dbpp in early 1994. This must have been one of the first books published on the Web. For a while, it accounted for a third or more of Argonne National Laboratory's web traffic.
What got me thinking about this ancient history is the following text:
The National Academies Press has for some time now been distributing the content of its monographs free on the web, and (thanks in part to a carefully thought-out strategy for doing that) it has seen its sales of print increase dramatically.
I've always thought that making DBPP available online must have increased sales. At least that is what I convinced my editor at Addison-Wesley would happen. However, I've never seen any relevant data. While the National Academies Press doesn't provide data (or explain their "carefully thought-out strategy": which sounds a bit like a cunning plan), this surely counts as anecdotal evidence.