A Graph Database uses [Graph](/blog/648/) [Structure](/blog/209/) with Nodes, Edges and [Properties](/blog/770/) to represent and store data, but there is not an easy way to visualize this.
There are various graph databases available:
- [Neo4j](/blog/690/)
- OrientDB
- HypergraphDB X
- DEX
- Titan
- InfoGrid X
Infinite[Graph](/blog/648/) X