I\'ve found links to several options on
2017 update: Cosmos DB now provides a good hybrid graph database solution in Azure. Cosmos DB used to be called Document DB until the Build conference in April 2017, when Microsoft announced graph and other capabilities. So you can use it as a classic document database, and you can now store your data as a graph and query it using TinkerPop/Gremlin. From .NET, you can query it using the Microsoft.Azure.Graphs API.
If you need to run outside of Azure, then you'll need to look at other options like Neo4j.