I'm Mark and I've been playing with Neo4j for about four years now. It's the most exciting DB technology I think I've every seen - and I've seen a lot!
When I started my computing career we were still using punched cards, paper tape, teletypes (real /dev/tty) and core store really was core store! OK you youngsters, go and Google those terms if you've no idea what I'm talking about. The first commercial relational database had just come on the market and practically no one used it. CODASYL network databases and COBOL were all the rage then.
I cut my DB teeth on ICL's IDMSX (the X standing for extended) which had some elements in common with Neo4j. IDMSX supported a network architecture rather than the hiearchic structure of IDMS, so creating graphs in the database was possible. Relationships were created when data was stored so no messy indexing required to follow 'SET's (chained records) just pointer chasing - and many a happy hour spent patching corrupt DB pages with a hex editor.
I now spend my days as a technical business analyst, spreading the good news about Neo4j and looking for new and exciting ways to use it.