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 provides GUI for various optimisation tools: AdvPNG from AdvanceCOMP, OptiPNG, Pngcrush, JpegOptim, jpegtran from libjpeg, Gifsicle and optionally PNGOUT. (To take advantage of PNGOUT you have to download it and set its path in ImageOptim's preferences, because license of PNGOUT forbids bundling of it with other applications.)

It's excellent for publishing images on the web (easily shrinks images “Saved for Web” in Photoshop) and also useful for making Mac and iPhone applications smaller.

Requirements:
OS X 10.6.8+
Intel

Also available is:
Universal Binary version 1.2.5 for OS X 10.5