Free Datascience books

I've been impressed in recent months by the number and quality of free datascience/machine learning books available online. I don't mean free as in some guy paid for a PDF version of an O'Reilly book and then posted it online for others to use/steal, but I mean genuine published books with a free online version sanctioned by the publisher. That is, "the publisher has graciously agreed to allow a full, free version of my book to be available on this site."
Here are a few in my collection:

• Mining of Massive datasets by Rajamaran, Leskovic & Ullman
• Bayesian Reasoning and Machine Learning by David Barber [website]
• Information Theory, Inference, and Learning Algorithms by David J.C. Mackay
• Foundations of Statistical Natural Language Processing by Manning & Schütze only sample chapters

While we are on the subject, I would be remiss of me not to recommend D.J. Patil's free minibooks/essays. While they are not the thick comprehensive tomes of those above, they are definitely worth the time to read.

• Data Jujitsu by D.J. Patil
• Building Data Science Teams by D.J. Patil

Finally, this is work in progress (just 3 chapters to date) but is one to watch: Network Science by A.-L. Barabasi.

Update [12/27/12]: adding in some additions from a hacker news discussion and the comments below (thanks guys):

• Introduction to Information Retrieval, by Manning, Raghavan and Schütze
• A first encounter with machine learning by Welling
• Gaussian processes for Machine Learning by C.E. Rasmussen
• The Elements of Statistical Learning, by Hastie, Tibshirani, Friedman -- grandaddy of them all
• Introduction to Machine Learning by Smola, Vishwanathan
• Think Bayes by Downey