digiKam - Professional Photo Management with the Power of Open Source
Smart Pix Manager - Smart Pix Manager is a powerful and reliable solution for the management and viewing of all documents, common images, sound (WMA, MP3), and video files (AVI, MPEG), etc.
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
StudioLine Photo Basic 4 - StudioLine Photo Basic 4 is a sophisticated image development tool that allows photo editing and multiple presentation options for personal usage.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
IrfanView - IrfanView ... one of the most popular viewers worldwide.