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

Punig is a free and portable application, a Graphical User Interface for OptiPNG, having OptiPNG embedded into its own executable. You can drag files to Punig (unsupported files are ignored) or you ::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

PhotoBatch is a free program that will let you perform batch processing, format conversion and renaming of image files. Scripts of commands, including input and output setup, can be saved and ::More