Mockuuups Studio is a simple tool which makes it easy to create professional product mockups (photos where your design appears in a phone or tablet, as in the screenshot).
There are no design skills required. Just import a file and it's instantly cropped and rotated to fit around 250 mockup templates, which are all then displayed in large preview thumbnails.
Most of these templates are only fully available in the $5/month, $48/year commercial version, unfortunately (you can export them now but they'll have repeated watermarks). Hitting "Free" displays the templates you can actually use, 22 when we sampled the program.
These are very limited, mostly iPhones, a few watches, two iPads, a single landscape device. But they look good, are a reasonable resolution (our test iPad shot was 3652x2435), may be exported in a couple of clicks and freely used in personal or commercial products.
Mockuuups Studio only has a few templates, but they look good, it's easy to create the finished mockup, and you're free to use this commercially.