If you are starting out with WSS/MOSS development, as I am, you might be interested in downloading some of the following resources.

Hands on labs:

• Hands on Labs for Developing Applications on Windows SharePoint Services 3.0: this is a very nice set of 10 focused hands-on-labs
• PPTs and Demos for Introductory SharePoint Developer Modules: another, smaller, set of HOLs

SDKs:

• Windows SharePoint Services 3.0: Software Development Kit (SDK)
• SharePoint Server 2007 SDK: Software Development Kit

White papers:

• SharePoint Products and Technologies White Paper: Implementing MOSS 2007 and WSS 3.0 Solutions
• Developing Custom Applications with SharePoint Server 2007