XnConvert - XnConvert is an easy image converter for graphic files, photos and images available on Windows...
Ralpha Image Resizer - High-speed image batch conversion tool
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.
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
Online Image Converter - Online Image Converter converts your BMP, JPG, PNG, GIF or ICO files quickly and easily.
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.