My favorite Excel keystroke combination. 

Pressing CTRL+SHIFT+= will not only insert cells (or rows or columns) but will automatically PASTE the contents of any cells I've highlighted and copied (with CTRL+C), but have yet to do anything with.

The original highlighted/copied cell I copied is remains untouched. Using CUT instead of COPY (by pressing CTRL+X) and when after highlighting the cells to move the contents of the "cut" cell into (by pressing SHIFT+RIGHT) CTRL+SHIFT+= is pressed the clipboard was inserted (moving the cells below down (the choice to move existing cells right or down is still required to be specified via the GUI, but Excel appears to default to the down direction. Finally, Excel DELETED the contents of the original cell.