1)   JPEG Imager 2.4.1
An interactive image compressor. Provides various compression controls and a real-time preview of a resulting image. May prove to be very useful if you need to optimize your images for publishing in the Web. Includes a set of image enhancement tools.
compress, optimize, jpeg, jpg, gif, png, view, edit, convert, picture,

 2)   PaletteMaker 1.3
PaletteMaker creates a common 256-colour palette from a list of RGB pictures. It uses an iterative and interactive procedure in order to optimize those colours that you judge most important. PaletteMaker is flexible and achieves high quality.
palette generator, color reduction, color quantization, dithering,

 3)   OptimizeBatch 1.0.0
OptimizeBatch is a versatile and robust tool for converting thousands of image files to any format of your choice in just a click with minute optimization in terms color maps, ditherings etc for use on the web and for e-mailing, storing, faxing etc.
Batch Converter, Optimizer, Web, JPG, GIF, PNG, TIFF, TGA, PCX, dithering,