Good book: "Programming Collective Intelligence"

This book is a great introduction to the techniques that I use almost daily in my own personal research and work for customers, and I can recommend it without reservation. The choice of Python for the examples is not optimum for me, but OK, especially because the techniques in the book for machine learning, categorization, clustering, filtering, optimization, support vector machines, etc. are mostly short and can be used as is or converted to whatever programming language that you need to use. The data used to present the book material is mostly from collaborative web sites. The book relies heavily on existing Python libraries and I like this approach since it mirrors rational software development practice: build custom code on top of existing libraries and software tools. Good book!