From the technical point of view this web gallery is one of the scripts simpler that one might implement, is sufficient specify the path to the directory containing the images within the configuration file. The images are automatically resized, are created automatically miniature, and it is even possible to show the metadata EXIF images. [more]
From the site "e2interactive.com"It is possible to download (And)2 photogallery and (And)2 gallery pro. The first is absolutely open source, and to tell the webmaster's license will remain unchanged. The second is a parallel project (I think that draws upon much of the code from the first), but it is not open source.