Building Simple Custom Approval Workflows with InfoPath 2007 Forms - http://msdn2.microsoft.com/en-us/library/bb629921.aspx

Creating and Editing Custom Document Information Panels from Office SharePoint Server 2007 - http://msdn2.microsoft.com/en-us/library/bb684925.aspx

Integrating Siebel CRM with Office SharePoint Server 2007 - http://msdn2.microsoft.com/en-us/library/bb613692.aspx