ImageBatch for U3
ImageBatch is a free lightweight batch converter for images, based on LibGD and EasyBMP graphic libraries. It currently supports JPEG, PNG, GIF and BMP formats. With ImageBatch you can not only convert your images from one format to another, but you can also resize, crop, rotate, flip them and draw watermarks on them as well.
ImageBatch is expected to work under any Windows platform, starting from Windows 95.