Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.
Photopus Pro - Photopus Pro is an easy to use batch image processing to simplify the process to convert, add watermarks (text and image), resize, transform, touch-up, rename, and apply effects to your digital images.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
GraphicConverter - Graphic Converter for Mac and Windows, can converts image formats BMP, JPG, GIF, ICO, PNG, TIF...
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
Batch Image Converter - Convert multiple images, photos, and pictures between 30+ formats: JPG, PNG, GIF, TIFF, BMP, JP2, J2K, TGA, PSD, RAW, DDS, PNM, WMF, ICO, SGI, HDR, LBM