Resize, convert, optimize, text-watermark your images with Visualizer Photo Resize
Visualizer Photo Resize is a free program that will let you perform batch resizing.
VPR will also convert and optimize your images, supporting JPEG, GIF, PNG, BMP, TGA, TIFF, PSD, PSP.
You can also use Visualizer Photo Resize to embed a text watermark in batch processing your photos.
A commercial version of the program offers even more features.