MenuMate is a nice system utility that displays a copy of the menubar when you click with an assigned button or when you press a hotkey combination. When you first run the application, the first thing you should do is assign a mouse button. The left and right mouse buttons can't be used, because the application doesn't want to interfere with Mac OS X's operation, but you can choose the middle button if you want. After the button is assigned, whenever you click it, a copy of the menubar will appear on your mouse pointer in the form of a contextual menu. All the options that you can access from the menubar at the top of the screen can be accessed using this contextual menu.
Once you have assigned a mouse button to MenuMate, you won't be able to use it for anything else. If you want to regain control of the button, you can free it by opening the "assign button" window again.
MenuMate should work with most Mac applications. I did my testing with Finder and Google Chrome, and the app was very responsive. The contextual menu was easy to navigate and accessing sub-menus was very fast.
MenuMate is one of the most popular productive tools available on the Mac App Store, and the users will probably benefit from using it a lot.