How to make a shortcut for “Zoom to 200%” in Photoshop CS6 on Retina
As you may know, Adobe updated Photoshop and Illustrator CS6 yesterday with full Retina Display support. If you've had a chance to play with it, you'll notice that PSDs now look something like this when scaled to 100%:

Retina Photoshop is now rendering documents at a 1:1 pixel ratio, which makes sense. It doesn't, however, work very well for “non-Retina” PSDs. They end up being scaled down to an impossible-to-edit size.
Fortunately, there's an easy fix! Just scale to 200%:

Easy, right? Well, it could be a lot easier.
Adobe has pre-defined keyboard shortcuts for “Zoom to 100%”, “Zoom in”, and “Zoom out”, but not for “Zoom to 200%” – something you'll likely use every day if you're editing non-Retina documents. Fortunately, there's a really easy fix.
1.
In Photoshop, go to Edit > Keyboard Shortcuts.

2.
You will be presented with all of the keyboard shortcuts available in Photoshop… did you know they're fully customizable? You're going to add one here. Find “View” in the list, then look for “200%” (near “Fit on Screen and 100%” zoom options).

3.
Put your mouse in the “Shortcut” field next to 200%, then type in a shortcut you'd like to use. I chose Opt+⌘+1 since ⌘+1 is the “100%” shortcut, so this new one will be easy for me to remember.

Press Add Shortcut and then press OK, and you're done!
Now you can continue to edit 1x PSD files with ease, without interrupting your keyboard shortcut zen. Enjoy.