Users can upload photos and organize them into albums, and they can search photos that have been posted in public albums and filter the results by license (any Creative Commons license, licenses that allow commercial use, licenses that allow remixing).
From the website:
Paint.NET is free image and photo editing software for PCs that run Windows. It features an intuitive and innovative user interface with support for layers, unlimited undo, special effects, and a wide variety of useful and powerful tools. An active and growing online community provides friendly help, tutorials, and plugins.