ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
ACDSee - ACDSee is an image viewer that uses very little system resources, and it has a small, sleek size that won't take up much space on your system.
Ralpha Image Resizer - High-speed image batch conversion tool
digiKam - Professional Photo Management with the Power of Open Source
Batch Image Resizer - Resize, crop, shrink, flip, exif-rotate, convert, enhance, process multiple pictures and photos with professional software! 120+ Actions, 30+ Image Formats
Flickr - image and video hosting website