This trick is for Photoshop:

Ever work on an image and need to zoom in to edit things at the pixel level? But then you have to zoom out to see how it looks at full size?

Not anymore. Use this tip.

Open an image.
Go to Window > Arrange > New window for...(filename)

This will open another copy of your current image.

Now, zoom one in and leave one at 100%.
Edit either one and they both change... it's the same image in two places.

Cool huh?