I just found out that Harry Mattison who is an expert Revit API developer has been running a very prolific blog called Boost Your BIM dedicated to developing on top of the Revit API. This is a good complement to the great The Building Coder blog run by Jeremy Tammik. Harry has also got a free Revit Add-in on Autodesk Exchagne Apps called Image-O-Matic. (Any product with "O" in the name is worth a look-see if you ask me.) Check it out and tell us what you think.