As a web designer sometimes it is helpful to see your design in context. That means viewing it from a new angle on a MacBook or a Tablet or a Desktop screen. You can always load up photoshop and comp together an image of your design and place it on top of a photo of a Desktop screen but there is an easier way.
Its called Place It
You just upload an image, crop it to fit the screen and your done. You now have an easy and quick way to create a visual mock up of your design on any type of screen.