Neo Technologies run little evening seminars to introduce their graph database technology and I took the liberty of attending one yesterday evening. You get a free book!
They’re based around the back of the Tate Modern, in an area which seems like an extension of Shoreditch with loads of start-ups and overpriced coffee.
It was a very interesting presentation, given by Rik Van Bruggen (Belgian), giving the background to the database and a really good demo using belgian beers as a dataset. Neo4j also has a community version that you can download as well as a free on-line course (with registration).
Rik also demonstrated a web site that visualises recommendations in Amazon.com, which is quite groovy.
The Laughing Programmer 