extreme programming explained: embrace change (k. beck)
A very interesting software development process. I'm convinced that it is often the best process to deliver running software.
ISBN 0-201-61641-6
www.aw.com

test driven development: by example (k. beck)
A nice approach for developing well designed software. TDD fits well into XP.
ISBN 0-321-14653-0
www.aw.com

refactoring: improving the design of existing code (m. fowler)
Every serious programmer should have this book on his desk and apply its refactorings whenever smells arise.
ISBN 0-201-48567-2
www.aw.com

design patterns: elements of reusable object-oriented software (e. gamma)
In my opinion, the intellectually most satisfying book on code design and programming ever written. But reading it is only half the story.
ISBN 0-201-63361-2
www.aw.com

pragmatic programmer: from journeyman to master (a. hunt & d. thomas)
A very valuable book that is easy and fun to read and that contains a lot of wisdom and experiences, at the same time.
ISBN 0-201-61622-X
www.aw.com

java threads (s. oaks & h. wong)
This is an excellent book to become familiar with Java's threading facilities. No pre-knowledge is necessary and things are explained really well. It does not cover patterns as does Doug Lea's book, though.
ISBN 1-56592-418-5
www.oreilly.com

java network programming (e. r. harold)
It explains how to use Java's network capabilities and additionally gives a good introduction to networking in general.
ISBN 1-56592-870-9
www.oreilly.com

just java 1.2 (p. van der linden)
A fast and advanced introduction to Java 2 which covers most of Sun's Java Certified Programmer topics.
ISBN 0-13-010534-1
www.prenhall.com

goto java 2 (g. krueger)
German introduction to Java 2 for people who are familiar with the basics of programming.
ISBN 3-8273-1370-8
www.javabuch.de

the c++ programming language (b. stroustrup)
The bible of C++ written by the inventor of the language himself.
ISBN 0-201-88954-4
www.aw.com

access 97 - das handbuch (n. nicol & r. albrecht)
This great book covers everything from database design to VBA programming and even a little bit of SQL.
ISBN 3-86063-135-7
mspress.microsoft.de

html 4.0 handbuch (s. muenz)
My favourite reference for HTML and DHTML with a lot of tricks, hints, and browser-specific information.
ISBN 3-7723-7514-6
www.teamone.de

javascript (s. koch)
An excellent and very carefully written introduction to JavaScript and DHTML in general.
ISBN 3-932588-26-6
www.dpunkt.de

dynamic html - the definitive reference (d. goodman)
You have to have it when you code web pages by hand using HTML, JavaScript, and DOM.
ISBN 1-56592-494-0
www.oreilly.com