
We all know and love Apple’s Preview program as an image viewer extraordinaire’, but did you know that it can also be used to create image files? Best of all, the creation process is quick and easy — in other words, very Mac-like — the way things should be.
If you have an image file on your clipboard (by using the "copy" command from virtually any program), you can simply use preview Preview and press Command-N. A new image file is created using the graphics on the clipboard, and you can then use File –> Save to save the image in a format and location of your choosing.
Source: "Use Preview to Create Image Files" by Rob Griffiths, published at Macworld.