Gallery 2 is a powerful and popular open source image gallery system with a large install size. Gallery2 is the successor to Gallery.
From the Author
Gallery is the next generation of open source photo sharing web applications. Gallery gives you an intuitive way to blend photo management seamlessly into your own website whether you're running a small personal site or a large community site. Hundreds of thousands of people and organizations are using Gallery to create personalized photo albums on their websites.
Authors website: http://gallery.menalto.com