The BizTalk Mapping Patterns and Best Practices book is a reference guide mainly intended for BizTalk developers to make their day-to-day lives easier. The book offers insights on how maps work, the most common patterns in real time scenarios, and the best practices to carry out transformations. The author has been working on this over the last one year, and his original idea of publishing these information as a blog changed in the due course to become a white paper, then finally to a “Community eBook” with about 400-pages and contributions from so many people.
NOTE: The download link will link you to the BizTalk 360 website for the download, however after I was added to a dozen junk mail mailing lists following this registration, I would really recommend NOT using this site. Please refer to my blog post about BizTalk360.
UPDATE: Sadly they have moved the object so you have to go through this process, please be aware of lots of junk mail following this.