The Field Guide to Genetic Programming was compiled from numerous sources to reflect the current state and practice of Genetic Programming. This book is an invaluable asset to anybody interested in Genetic Programming. I highly recommend it. It is available for free online, but it certainly doesn't hurt to have a hard copy.
We greatly appreciate this sort of support. It's nice to know that people are finding the Field Guide useful, and are willing to spread the word. Many thanks to everyone who's put a little of their energy into our project.
Quite remarkably, the Field Guide continues to sell steadily on Amazon despite being freely available in multiple formats. Our sales rank on Amazon.com is (as of today) #198,789. This may not sound like much, but for a quite specific technical book in an area of computer science most people haven't heard of this is pretty darn excellent! A quick survey of some of the other heavy hitters in the EC book list shows that they're all ranked over 200K, with many much higher (like over 500K). That said, Melanie Mitchell's new Complexity: A guided tour (which is a general audience book) is ranked 2,981, which is a really excellent achievement - congratulations to Melanie!
If you're a reader of either the PDF or printed version and would like to lend a hand, feel free to leave a short review on something like Amazon - it's definitely appreciated.