Beyond fraud detection, centrality algorithms can also be used in many contexts. We have already talked about influencer detection in a social network. By now, you may understand why PageRank is a good choice in that case since it not only takes into account a given person's connections, but also the connections of those connections... In this case, overall, the information spread will be faster if it starts from a node with a higher PageRank.
Biology and genetics are two other important fields of application of centrality. For instance, when building a network of protein interactions inside some yeast, researchers can determine which of these proteins are more essential to the yeast and which are not vital. Many other applications of centrality, especially PageRank, have been explored in the domain of genetics to determine gene importance in some given disease, for instance. See the article PageRank beyond the web (link in the Further...
