JPGCrunk : jpgcrunk is a tool for crunking images.
Caire : Caire is a content aware image resize library
PunyPNG : PunyPNG is a free website optimization tool that dramatically reduces the file size of your images without any loss of quality.
Trimage (lossless) image compressor : Trimage is a cross-platform GUI and command-line interface to optimize image files via optipng, pngcrush, advpng and jpegoptim
