Six Negative is an open source photo management tool for storing, sorting and publishing images (although it can also handle videos and audio files). The application is written in PHP/MySQL.

Download the latest version for free; you'll need a Linux hosting environment and access to MySQL. For help with your installation, visit the support wiki.
Six Negative was designed for the prolific photographer whose storage and publishing needs exceed the feature-sets and usage restrictions of social image sharing tools like Flickr, Picasa and Facebook. Six Negative doesn't necessarily replace those tools; rather, it exists upstream as an image archiving platform and can be used to centralize assets which are then distributed through social media.
Six Negative stores images, videos and audio files within a logical directory structure on your server and preserves a variety of metadata, such as:
Six Negative is written by Timothy Quinn.