How to extend windows explorer functionality?

Question

How would I go about extending the functionality of windows explorer in XP?

Is there some way whereby I could create a "plugin" of some sorts that could hook into explore.exe to add additional folder browsing functionality? What language could I use to achieve this?

This is an expansion of a question I asked here.

Answer 1

There's a great series of tutorials on CodeProject which might help you. C++ is required there.

Answer 2

There is an old O'reilly book called 'Visual Basic Shell Programming' that explains the API's for this in some detail. While taken from a VB6-centric point of view, the API's are all exposed through COM, so they can be used from any language that supports this. This article discusses using the windows shell with .Net and a tool to build an interop assembly.