In case you have not noticed, I would like to point out one important specialised addition to the Revit 2014 SDK: the new Structural Analysis Software Developer Kit.
It lives in its own sub-directory Structural Analysis SDK and consists of documentation, sample code and Visual Studio templates for two main components:
Here is an overview of the sample applications provided with this toolkit:
If you are active in this area, this provides a big lump of functionality you definitely need to be aware of, similarly to the REX SDK and content generator.
In a related vein, here is a question that just arose today:
Question: I would like to start working programmatically with Autodesk Robot to read relevant data result from structural elements such as beam, column, foundations, slab etc.
Where can I find some information about that, please?
Answer: Please take a look at the discussion of the Robot Structural Analysis API.
Addendum: Here is the complete Robot API documentation and tutorial from April 2010, copied from the API Tutorial thread on the Autodesk Robot Structural Analysis discussion group. Note that this information is pretty dated by now, so I would not recommend putting in any significant effort developing new projects based on this today.