Pie menu
A pie menu (sometimes called radial menu or marking menu) is a circular popup menu where selection depends on direction. A pie menu is made of several "pie slices" around an inactive center and works best with stylus input, and well with a mouse.
Benefits
Pie menus are faster and more reliable to select from than linear menus, because selection depends on direction instead of distance. The circular menu slices are large in size and near the pointer for fast interaction (see Fitts' law). Experienced users use muscle memory without looking at the menu while selecting from it. Nested pie menus can efficiently offer many options, and some pie menus can pop up linear ones. Pie menus are shown only when requested, resulting in less distraction and clutter than toolbars and menu bars that are always shown.
Sample
The following is a sample Javascript implementation of a pie menu, built using the latest trunk build of MooTools. Its usage should be fairly self explanitory - if you're unsure, check the source of this page and the actual code for more information. The code new PieMenu('containerclass', 'menuid'); should generally be sufficient.
How to use the sample below: click on a section to bring up the pie menu. Press the 'stop' button in the menu to make an item disappear. Click here to make all the items re-appear.