Some graphics applications (like 3D modeling package) have pie-chart like menu system; for example, if you type SPACE, an overlayed menu appears around the mous

Some graphics applications (like 3D modeling package) have pie-chart like menu system; for example, if you type SPACE, an overlayed menu appears around the mouse cursor and just moving a mouse a bit to that direction and release SPACE triggers that item (you don't even click). Watching the experienced users using that interface is just amazing. They don't read the menu items; they know which direction is what by heart, probably in muscle memory.