Here is a short note to point out that Guy Robinson has posted some interesting Revit API solutions on his blog Bolt out of the Red. One that I found especially useful is on how to get a bitmap or thumbnail from a Revit project or family. Now he started a series on saving user specific configuration data for Revit commands using standard .NET functionality from the System.Configuration namespace, which has a number of pitfalls and requires some understanding of how Revit add-ins are loaded into the Revit AppDomain etc.