I have books  referenced on my book page here:
www.mousetrax.com/books.html, but it is in need of updating! So you can just
search Amazon for "John Walkenbach" to find all his books.

Plus, here's other Excel VBA gurus (and friends) have published very good
books to search Amazon on are....

* Stephen Bullen
* John Green
* Rob Bovey
* Robert Rosenberg

In fact, here's one the group above all did together:
Excel 2003 VBA Programmer's reference  (Programmer to Programmer)

And from the stories I hear<smirk>...they put their heart and soul into this
one:

Professional Excel Development : The Definitive Guide to Developing
Applications Using Microsoft(R) Excel and VBA(R)

When it comes to Excel VBA dev, you can't get much better than the list
above.