Amazon Dynamo Database (also known as DynamoDB or DDB) is a fully-managed NoSQL database service. Dynamo Database is known for extremely low latencies and scalability.
According to Amazon's DDB pages, DynamoDB makes it simple and cost-effective to store and retrieve any amount of data, and serve any level of request traffic. All data items are stored on Solid State Drives (SSDs), and are replicated across 3 Availability Zones for high availability and durability.
Notable users include The New York Times, Heroku and IMDB.
See a video introduction to Amazon Dynamo Database: