1. A Road Tool, that you just define the width (and also cross section shape) and draw the path/spline on the plan view, and it will automatically be attached and conform to the terrain. (Sort of like the tools they have in Command and Conquer General Editor)
2. Re-confurable key menu. This is desperately needed. Every other app worth it's salt have it, why revit doesn't??
3. Draw along surface spline tool, so you can "extrude" shapes out of terrain, eg. fences, post, etc.
4. SketchUp like interface - I must be dreaming about this every night... just basically let you draw lines in 3D space that snap to the 3D axis and form 3D faces. Revit's family editor badly need this for easier family creation. Also a more powerful polygon tools (like from MAX) are needed too for more complex editing/object creation.
-RM