[embed]https://twitter.com/andyhickl/status/303691512284327937[/embed]
Color me skeptical, but Reco4j might be worth a test drive:
Reco4j is an open source project that aims at developing a recommendation framework based on graph data sources. We choose graph databases for several reasons. They are NoSQL databases that are “schemaless”. This means that it is possible to extend the basic data structure with intermediate information, i.e. similarity value between item and so on. Moreover, since every information are expressed with some properties, nodes and relations, the recommendation process can be customized to work on every graph.
Hmmmm. But are they high quality recommendations for every graph?