Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.
ConvertIcon! - Converticon is a simple icon utility.
FastStone Photo Resizer - Convert and Rename images in batch mode Support JPEG, BMP, GIF, PNG, TIFF and JPEG2000
GenFavicon - Generator Favicon.
ImageMagick - ImageMagick is a software suite to create, edit, and compose bitmap images.
Ordinatore - Those who want to tidy up their Macs will surely love this application.