I just posted as a whitepaper an Inventor study guide covering some slightly advanced topics. See
my post announcing it for more info, or go to the
technical whitepapers.
I have some more of this kind of material which I plan to post when I get the time. Inventor 101 fills in some of the gaps in Autodesk's Getting Started tutorials, and Inventor 301 goes into assemblies, constraints and a little sheetmetal (but the document needs a bit of work before it goes public).