our.imgSeek.net is free and will always remain so. It was created as an experiment on social photo bookmarking. Think of Flickr! meets reddit meets del.icio.us.
Everything explained on the next section is running on a single cheap shared hosting account. I've managed to keep CPU and bandwidth usage minimal so far but I'd definitely love to have the challenge of making it scale on some dedicated servers, but I can't afford it right now.