ubuzz Digital
Free Drag-and-Drop Tool To Create Realistic Looking Images
Design resource site, Icon8, has created a useful drag-and-drop tool called Moose - Photo Creator that lets you create realistic photos using png images.
Pick from hundreds of backgrounds.

Add objects:

People:

You can rotate, scale and flip each individual image. Download your creation in a png or psd format.
Try it out here. Happy Creating!