Picasa from Google will allow you to edit and resize your photos in bulk.
The new version of Google's photo editing software is available as a standalone free download. When you install the latest update of the software, Picasa will instantly locate and organise all of the pictures on your computer. This tool is not just for picture resizing; it's a complete solution for photo management, multiple image editing and quick picture searching.
Professional Photo Editing Tool
Also consider Adobe Photoshop for editing your photographs, as used by professional web designers and artists around the world. Photoshop is certainly not a freebie, but it is the preferred choice for thousands of website design experts and creative art directors within small and large design studios. It's also popular with professional digital photographers.
The product includes a wealth of tools for retouching images and creating unique text effects. For the ultimate control over your photographic images, picture menu buttons and web graphics, Adobe Photoshop is recommended.