ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
PNGGauntlet - -Combines PNGOUT, OptiPNG, and DeflOpt to create the smallest PNGs
Ralpha Image Resizer - High-speed image batch conversion tool
jStrip - jStrip is a free tool to reduce the file size of JPEG images without sacrificing image quality.
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.