Another custom book that we created for the IOD conference was called "DB2 9: pureXML Overview and Fast Start". This book was also in a very small printed format that is a collection of key papers about XML. We ran out of these books at the conference as well and continue to get requests for additional copies.
Fortunately for this book, we used the ITSO to create an electronic format of the book, so you are still able to read the content: http://www.redbooks.ibm.com/abstracts/sg247298.html?Open
Thanks to Rav Ahuja for initiating this custom book. I'm working on another one right now that I'll tell you about when it gets closer to becoming reality :)