We are in an era of unprecedented innovation in databases. Data-intensive companies are grappling with whether the many new options — NoSQL, Key-Value, Document, Column Family, Column-Oriented — are appropriate for them. The commercial success of Facebook and LinkedIn makes graph databases a hot area of investigation. Unlike many new databases, they are not a variation on or a simplification of relational databases. Instead they require new ways of thinking and modeling data. In return they can answer truly novel questions.