A guide to NoSQL offerings
Amazon Web Services: DynamoDB is a NoSQL database service that makes it simple and cost-effective to store and retrieve any amount of data and serve any level of request traffic. Users simply tell the service how many requests need to be handled per second, and the data is spread across commodity hardware and replicated for fast processing and fault tolerance. DynamoDB’s throughput guarantees and single-digit latency make it a good choice for gaming, mobile and other applications.
Basho Technologies: Riak is an open-source database that uses a key-value model for object storage. It combines operational simplicity with high availability, scalability, and fault tolerance. Riak can be used to store text, images, JSON/XML/HTML documents, user and session data, backups, log files, and more. It provides a straightforward RESTful API as well as a protocol buffers interface. Riak has several features for querying data including Riak Search, secondary index, and Map/Reduce.
BrightstarDB: BrightstarDB is a fast, embeddable, scalable NoSQL database for the .NET platform with code-first data model generation. It supports Windows Phone 7, Windows Phone 8 and .NET 4.0. BrightstarDB uniquely provides a Full Entity Framework model over the underlying data store so developers can take advantage of a NoSQL store and still work with typed objects when building applications. Its schema-free triple store provides developers the flexibility to decide what data is stored and how it is connected. Source