Extract and Save App Icons

You can extract a Mac application icon from Finder and copy it into Preview for high resolution Mac application icons. From there you can save it in many different file formats.
  1. Open your finder and choose an application.
  2. Simply click Control-C to copy and then open Preview and click Control-N.
Example: Copy the Dashboard Icon.

Now after you copy it by pressing Control-C, open Preview and simply press Command-N and this is what you get:

You can extract any Mac application icon into Preview in full high resolution and then save it in the file format of your choice. In fact you can paste any image into preview not just an application icon.