ImageOptim - Faster web pages and apps.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
XnConvert - XnConvert is an easy image converter for graphic files, photos and images available on Windows...
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
JPEGmini - JPEGmini - The Photo Optimization Tool Trusted by Tens of Thousands Image Perfectionists
Ralpha Image Resizer - High-speed image batch conversion tool