LinPHA is an easy to use, multilingual, flexible photo/image archive/album/gallery written in PHP. It uses a MySQL database to store information about your pictures. It comes with a HTML based installer, so you don't need experience in setting up SQL DB
MG2 / MiniGal is a FREE and easy to use PHP image gallery script. It is being offered as a non profit service for photographers and webmasters who want a simple, fast and good looking image gallery on their website.
Gallery is a web based software product that lets you manage your photos on your own website. You must have your own website with PHP support in order to install and use it. With Gallery you can easily create and maintain albums of photos via an intuitive interface. Photo management includes automatic thumbnail creation, image resizing, rotation, ordering, captioning, searching and more. Albums can have read, write and caption permissions per individual authenticated user for an additional level of privacy. Give accounts to your friends and family and let them upload and manage their own photos on your website!