CThruView Transparent Image Viewer - CThruView is a free transparent image viewer that allows mouse clicks to go through the image.
Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
LayerX - An intuitive app to display transparent images on screen.
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
Osiva - Osiva" is an acronym that stands for "Overly Simple Image Viewing
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.