I came across this jewel last week. A must have for a MOSS developer. Following is the excerpt from the download page.

Learn how to build a business solution leveraging a broad range of Microsoft Office SharePoint Server 2007 Enterprise capabilities. This white paper focuses on the real-world example of an application to help consulting companies track client engagements and business performance. But the insightful lessons learned and best practices will apply wherever your next SharePoint development project takes you.

Topics include Office SharePoint Designer 2007, workflows, Excel Services 2007 and the Enterprise Search API. Whether you are a SharePoint development guru or a Microsoft .NET developer evaluating the platform, this white paper has something for you.

Check it out @ Developing Custom Applications with SharePoint Server 2007