I've taken the liberty of listing each Revit 2011 category that does not contain types for anyone looking to impress their spouse with some pointless trivia (more for my own future reference than anything else).
Can anyone name the one category that only has types and no instances??....
INTERNAL AREA LOADS
INTERNAL LINE LOADS
INTERNAL POINT LOADS
MASS EXTERIOR WALL
MASS INTERIOR WALL
FACIAS is the category that only contains types and no instances...