A long time ago, in the far distant past, before the advent of the Family API, Revit API developers and family content creators were two entirely separate camps with their own secret arts and magic charms. Since then, we have been given programmatic access to the family creation functionality, and the synergy in the union of these two camps is growing.
This makes it all the more important for any developer to have an in-depth understanding of the family creation process. One effective way to build this kind of understanding is to work through the Revit Families Guide. The latest version provided is for Revit 2010. It includes readme files, documentation, and datasets for hands-on exercises, all of which are provided in fourteen languages and both metric and imperial versions. Strongly recommended for anyone diving into Revit customisation or programming in any depth.
Here is also a short (8 minute) live training tutorial:
For further study, there are also some commercial training sessions and DVDs available for purchase, for instance from Paul F. Aubin, CADclips.com and Steve Stafford's AEC Advantage.
Many thanks to Pawel Piechnik, Autodesk Sr. Structural Product Manager in Krakow, Poland, for highlighting this to us!
Here are some other videos and documents that may be of interest to you highlighting the value of BIM for MEP and structural engineers.
Another useful asset is the Project Storm for Revit Structure, which was recently published on Autodesk Labs, and for which an update is now available. Here are two short press reviews on it in Modern Steel and Construction and The Revit Kid.