CThruView Transparent Image Viewer - CThruView is a free transparent image viewer that allows mouse clicks to go through the image.
Flickr - image and video hosting website
LayerX - An intuitive app to display transparent images on screen.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Osiva - Osiva" is an acronym that stands for "Overly Simple Image Viewing
Google Photos - All your photos are backed up safely, organized and labeled automatically, so you can find them fast, and share them how you like.