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
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
24 Ways - An advent calendar for web geeks
Ralpha Image Resizer - High-speed image batch conversion tool