If they're unused, why should you ever see them?
You start with full menus that learn over a day or a week or with empty menus. Click or hover over an area at the top or bottom of the menu to show more(most recent)/all.
Rearrange or add recently/frequently used menu entries to the top/close to mouse.
-Every menu can be pulled off to float (option always on top), and autohide (scroll or fade to % opacity)
-Dock to window and screen edges and autohide