It has an innovative and intuitive full-screen mode that provides quick access to information and functionalities via hidden toolbars that pop-up when ever your mouse touches any of the four screen edges.
Other FastStone Image Viewer features includes a high quality image magnifier, musical slideshows with over 150 transitional effects, lossless JPEG cropping & re-sizing, drop shadow effects, scanner support, histogram info and much, much more.
It supports a ton of image formats including RAW.
You can download it here.
I want to thank Stew Turner for bringing this one to our attention.
You can visit Stew's website here and his blog here.