UXmas - An advent calendar for UX folk
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
25DaysOf - A customizable advent calendar, for everyone
Batch Image Resizer - Resize, crop, shrink, flip, exif-rotate, convert, enhance, process multiple pictures and photos with professional software! 120+ Actions, 30+ Image Formats
24 Ways - An advent calendar for web geeks
Ralpha Image Resizer - High-speed image batch conversion tool