OptiPNG is a free command-line tool (gui extensions are avalaible), that will help you optimize PNG files, to reduce their size to a minimum without losing significant (perceptible) information. ::More

Image Tuner is a simple and free program that will help you rename many images at once to get rid of standard naming patterns, resize them for uploading to social networks, phones and forums, ::More

Futurix Imager is a free image viewer, capable of opening more then 40 file types, including the most common (GIF, JPEG, PNG, TIFF, JPEG2000, raw, DNG). It can also print, scan, perform some basic ::More

WildBit Viewer is a free (for personal use) image viewer with slide show and editing abilities. The interface is nice and easy to use, featuring a folder / file list and a thumbnail viewer. The ::More

Multiff is a freeware that can edit multipage TIFF files. You can view TIFFs with Image and Fax viewer bundled with Microsoft Windows, but this software cannot perform page manipulation, such as ::More