You know, I read Refactoring and really enjoyed it.
I also keep a copy of UML Distilled close by, and recommend it as a must have. It's a great reference, but man, just try reading it. It's just brutal reading. Martin Fowler wasn't joking when he used the
word 'Distilled' in the title.
But I was surprised when I realized both books were written by the same person. Clearly, a 'distilled' book on UML was the goal, because Refactoring was a much more enjoyable simply as a pure read.
One book I might suggest is Java Modelling in Color by Peter Coad.
It's amazon reviews are somewhat appropriate, but what it does is give you insight on how to design an object model at a very complex level. If you don't know your stuff, this book will leave you in the cold.
The other great thing is it has about 100 real, complex object models with real sequence diagrams. In your real life work, you can open a section of this book and pull out a very complete, and very complex object model and class diagram that will address problems you never thought of, and make you look like an absolute star.
I plan on referencing it often as I put together my SCEA 5 submission.
-Cameron McKenzie