I'm referring to the Nudge feature in Revit of course. Even seasoned Revit users seem to forget how useful this is. Specifically this feature allows you to nudge a selected item or items instead of using the move command or dragging it/them to a new location. All by just pressing those trusty Arrow keys on your keyboard.
Nudge isn't an arbitrary movement either. Based upon how much you are zoomed in or out Revit will use the Snap Increment to Nudge an exact distance. Revit will use a fraction of a snap unit when you change your zoom as well. If you wish to nudge a smaller or larger distance you can zoom in or out a bit. (see the default increments in the image)

Using the Shift key and one of the Arrow keys will nudge 10x the nudge without shift, go fartherer more quickerer...
So next time you need to tweak a piece of text, a viewport, a wall...well anything really...think Nudge Nudge Wink Wink??
P.S. I've added clarifications to the above text on April 22, 2006 because both Leonid Raiz and Irwin Jungreis (Revit's founders) provide invaluable insight in posts at the AUGI forum.