Java EE 6 Pocket Guide by Arun Gupta; O'Reilly Media
The Java EE Pocket Guide is a summary of all of the features of JEE6, but it is by no means comprehensive.
This book is clearly written, as are all books by O'reilly. But I don't see the value of it, as it covers all aspects of J2EE, but with very little detail. I felt like I was bombarded with so many acronyms, one after the other, that it made my head spin. I would suggest using the J2EE Developer Guide as a reference before recommending this book.