The Fotonauts feature set allows individuals to collaborate and take the world's pictures from Flickr, Picasa and other services and create structured datasets with metadata. When you have tens of thousands of photos organized and structured by people, you have a huge dataset, which also becomes an index--a Wikipedia of photos.
In addition, fotonauts public albums can be turned into widgets and easily distributed to any Web page. Fotonauts provides a unique URL for each album for sharing.
At the core of fotonauts' search engine effort is tagging that comes from adding relevant content, such as maps and Wikipedia content, to images and albums and applying tags from other services. Fotonauts also created its own ranking algorithm, ImageRank, which combines tags and usage data to deliver the most relevant results.