Coppermine Photo Gallery

Coppermine is a free, multi-purpose fully-featured and integrated web picture gallery script written in PHP using GD or ImageMagick as image library with a MySQL backend.

Details and Download here.

SelectaPix Image Gallery

SelectaPix is a free (GPL Licence), highly configurable PHP/MySQL image gallery system which can be integrated into your existing site in minutes. The password-protected admin section allows you to upload up to 10 jpeg images in one go, and arrange them into albums and sub-albums.

View Demo and Download.