TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
FotoFlexer - FotoFlexer is the most powerful online photo editor in existence.
ImageOptim - Faster web pages and apps.
Fun Photo Box - FunPhotoBox is a free photo editing device where you can make clever pictures from your photographs.
TinyJPG - Compress JPEG images with perfect quality and file size
piZap - Free online photo editing software.