From the website:
GraphDB-Bench is an extensible graph database benchmarking tool. Its goal is to provide an easy-to-use library for defining and running application/domain-specific benchmarks against different graph database implementations. To achieve this the core code-base has been kept relatively simple, through extensive use of lower layers in the TinkerPop stack.
Should be useful for experimenting with different graph database implementations as well as generating test graphs with different typologies.