IrfanView - IrfanView ... one of the most popular viewers worldwide.
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
ImageGlass - You can use Image to view your digital images and photos of many different formats.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Imagine - Imagine Freeware Image & Animation Viewer for Windows
Fragment - A powerful image viewing suite with advanced metadata info