Just what I was looking for...

It does one thing well and it does that one thing extremely fast. Switching display resolutions in Mountain Lion is kind of a pain and you must go to the display preference pane as they took away the option to have the displays in the menu bar unless you are mirroring two displays. With this utility you can switch quickly between the current resolution and the 2x HiDPI mode of your display. Nothing more but it is just what I was looking for.

Great for taking high-res screenshots or testing websites with Retina Graphics.

Flugo about ResolutionTab