While catching up with new items in my RSS reader I learned that Patrick Tisseghem has just released another fantastic article series about WSS3 on MSDN:

• Development Tools and Techniques for Working with Code in Windows SharePoint Services 3.0 (Part 1)
• Development Tools and Techniques for Working with Code in Windows SharePoint Services 3.0 (Part 2 of 2)

These two articles go over the development process for WSS3 and MOSS 2007: setting up the development environment, basic development tools (Visual Studio Extensions for WSS3), using features, custom field controls, packaging it all into solutions (.wsp) and even a small sample on setting Code Access Security for web parts. Wow!
A must read for everyone starting out or already doing WSS3 development.

At the same time I've also updated my own list of WSS3 and MOSS 2007 resources I'm trying to keep up to date. It's not yet an extensive list of tools available but I'm trying to keep the list updated with tools I've already tried out.