Software to losslessly optimize batches of image files
ImageOptim?

ImageOptim optimizes images — so they take up less disk space and load faster — by finding best compression parameters and by removing unnecessary comments and color profiles. It handles PNG, JPEG and GIF animations.
ImageOptim seamlessly integrates various optimisation tools: PNGOUT, AdvPNG, Pngcrush, extended OptiPNG, JpegOptim, jpegrescan, jpegtran, and Gifsicle.