From Geek Development Labs:
Watermark Studio is an easy to use image watermarking software to add visible and transparent watermarks to multiple images in a batch. It allows you to protect your photos from unauthorized distribution using one of the included or a custom watermark which could be added on any position and size. In addition to graphics and logos, it also supports direct text watermarks, which could be entered directly or imported from an image. Watermark Studio can also can be used to create thumbnails, resize and convert images. There is only one click required to process a whole directory of images and photos.