This is one of my favorite services for creating a product image. They have over 200 template product shots that incorporate multiple devices, and a simple to use interface. After selecting the product shot template, you can upload individual images for each screen until you’re happy with the design.

You can create quick mockups for for T-shirts, mugs, computers, etc. There’s also video mockups you can create with a click of a button. I like to do screenshots of websites on computer screens for sales pages and product promotions. For instance, let’s say I want to show one of my demo blog sites on a MacBook Pro laptop computer. I just type in the URL to my site and Placeit shows me what the site will look like on a variety of MacBook Pro mockups. Then I just choose the one I want, pay the fee and then download immediately. That would take a lot of time to do in Photoshop or other graphic editor. Placeit makes it VERY easy.

Get more info here.