To provide a lower-cost (read "free") alternative to MediaPro, I wrote Gallery Monger, a stand-alone app that can turn folders of images (or selections from an iPhoto catalog) into a finished Web gallery. Gallery Monger is template-based, so you can easily edit the existing templates or create your own. MediaPro still scores over Gallery Monger with its thorough support for EXIF metadata, so if you want to display image stats, Gallery Monger won't be able to extract that information for you. For quickly creating a nice-looking gallery, though, this software may be just what you need.
Mac OS X version 10.3 or later