As I was writing the 3rd edition of my Exchange and Outlook book I decided to include SharePoint in the mix.  At the time, SharePoint Portal Server 2001 shared the same storage system as Exchange (SharePoint is now built on SQL).  To that end, I wrote six chapters:

Chapter B: Programming SPS 2001: Overview
Chapter C: Programming SPS 2001: Seach and Workflow solutions
Chapter D: Digital Dashboards
Chapter E: SPS 2003: Overview
Chapter F: SPS 2003: Programming WebParts
Chapter G: SPS 2003: Object Models and Search

Just for the SPS 2003 section, that's 157 pages of free, wait a minute free?!?!?!?! content???  Yes, MSPress told me my book was too big to print with all my content (1800 pages in the book itself, over 200 additional pages for free off the web).  So, I said what the heck, I wrote the content, I love SharePoint, jam it on the web for free.

Why do I write this entry?  To get the word out so people use the free content!  Not only do you get all those pages but there are sample applications.  I even wrote them in both VB and C#!  Here's the short list of samples from the web part section where I tried to cover basic, intermediate and advanced topics:

Simple web part
Custom properties and custom ToolParts web part
Custom ToolPane web part
Client-side script web part
Custom menu items web part
Connected web part (using the row provider and includes both a consumer and producer)
Async web part (Shows you how to spawn threads and perform all your operations async so you don't slow down SPS on load)

Now, you may be asking how you get your hands on all this juicy content.  Simple, download the samples for the entire book here which includes not only the SPS content but also all the Exchange/Outlook samples.  For the chapters, download the content from here.

Take a look and provide feedback.  I'm thinking of updating the content for Office "12" but will only do so if people find it useful.

Enjoy your newfound wealth of information about SharePoint!