iFotosoft Photo Viewer!

XnViewMP is a free software to view, organise, convert graphics and photos files or to create slide show, contact sheet, HTML pages.

FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor. It has a nice array of features that include image viewing, management, comparison, red-eye removal, emailing, resizing, cropping and color adjustments. Its innovative but intuitive full-screen mode provides quick access to EXIF information, thumbnail browser and major functionalities via hidden toolbars that pop up when your mouse touches the four edges of the screen. Other features include a high quality magnifier and a musical slideshow with 150+ transitional effects and more. »

Shotwell is an open source photo organizer designed for the GNOME desktop environment.

Apowersoft Photo Viewer supports various image formats and PDF files. You can also process images in batch, take screenshots and upload/share images in seconds.

Cornice is a cross-platform image viewer written in Python + wxPython + PIL. It has been inspired by the famous Windows-only ACDSee .

Phiewer