Visio Guy Fellow Visio MVP (one of the original shape masters) Chris Roth runs a must see website.
It contains a showcase for his shape master talents and has many good articles for shape developers. The website also maintains a set of forums that
have filled the gap when the Microsoft newsgroup closed.
Website with Visio Tutorials (other than Microsoft websites)
CADinfo.NET:This site has several articles, tutorials and tips for Visio.
DVS: "Developing Visio Solutions" is the best starting point for learning about programming with Visio. It's free and comes with Visio. If you did not receive it as a printed book, an Acrobat version of the book is included on the Visio CD. This has been replaced on later versions of Visio by the book "Developing Microsoft Visio Solutions". The content is also available on the MSDN website.
"Visio 2000 Developer's Survival Guide" by Graham Wideman (Trafford Publishing): Graham's book is an excellent companion book to DVS. It provides more insight into several Visio features.
"Visio 2002 Developer's Survival Pack" by Graham Wideman (Trafford Publishing): Graham upgraded and expanded his book for Visio 2002.
"Visio 2003 Developer's Survival Pack" by Graham Wideman (Trafford Publishing): The next version of Graham's book updated for Visio 2003. A definite asset for anyone doing serious development with Visio.
"Visio 2007 Bible" by Bonnie Biafore (Wiley Publishing): The big book for Visio users.
"Visualizing Information with Microsoft Office Visio 2007" by David Parker (McGraw Hill Publishing): David has taken up Graham's writing style and gone into an indepth study of some of Visio 2007 new features, Data Graphics, Pivot Diagrams and a lot more.
"Microsoft Visio 2010 Business Process Diagramming and Validation" by David Parker (Packt Publusking):Visio 2010 introduced a new feature, validation rules. Though Visio 2010 comes with some validation rules, David expands on how rules are created and provides tools for creating and managing rules. VISIO RULES!
"Step by Step Visio 2010" by Scott Helmers (Microsoft Press):A good introduction by fellow Visio MVP Scott Helmers.
"Using Visio 2010" by Chris Roth (Que Publishing):Another good introduction by fellow Visio MVP Chris Roth.