The Microsoft Office 2000/Visual Basic Programmer's Guide describes how to use the applications and components in Microsoft Office 2000 to build custom solutions. This guide is the definitive resource for developers who are creating custom solutions based on Office applications. From the overall design of your solution to the nitty-gritty details of implementing it, this book tells you what you need to know to get things done quickly and productively.
This is a great resource for Office VBA developers. Among other valuable chapters it includes one of the only references I have been able to find for custom classes and objects.