Add measurement of an edge or maybe space between 2 components as a parameter.
It is dumb to have to create a sketch just to create a driven dimension so that a certain measurement can be referenced.
This is found here: http://forums.autodesk.com/t5/Inventor-IdeaStation/Add-measurement-as-parameter/idi-p/3740472,
but I don't believe it got the attention it deserves!!