The following video outlines the core-concepts behind online photo-sharing sites. It suggests that they are great for contingency too! Sites like Flickr are a great way to share the joy of images and creativity. Some of my photos are online too.
I also wondered if such sites could also be used internally, say a department developing a set of learning slides, e.g: capturing business workflows or critical issues. If they could be loaded onto a learning management system, they could serve as great project or employee induction support mechanisms.