ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
Squash 2 for Mac - The easiest way to compress and optimize images for the web
Batch Image Resizer - Resize, crop, shrink, flip, exif-rotate, convert, enhance, process multiple pictures and photos with professional software! 120+ Actions, 30+ Image Formats
Icecream Image Resizer - Image resizer by Icecream Apps is a program to resize images fast and free. Windows version. Free Download.
Phatch - Phatch = Photo & Batch!
Resizing.app - Image resizing has never been so simple with free online resizing.app. Convert, optimize, resize images with ease and for absolutely free.