JavaSpaces Principles, Patterns and Practice by Feeeman, Hupfer and Arnold.
I found this book very helpful when setting out on the unfamiliar sea of Spaces programming.
Unfortunately it is a bit dated but there is nothing newer.
Professional Apache Tomcat 5
Published by Wrox in 2004 ISBN: 0-7645-5902-8. I have found
this to be a very handy reference that fills in the gaps in the online Tomcat
documentation. It actually covers both Tomcat 4 and 5 - very important since both are in wide use.
JESS in Action by Ernest Friedman-Hill.
A very clear explanation of the rather tricky topic of Expert Systems (Rule-Based Systems)
with extended practical examples in Java using the JESS library.
Java Message Service by Richard Monson-Haefel and David A. Chappell.
This book was a big help to me when I created the demonstration of SOAP message transmission
with JMS for chapter 8 of the SOAP book.