Amazon Web Services provides a number of NoSQL database alternatives for developers. You can run fully managed non-relational services like Amazon’s DynamoDB or work with Amazon Solution providers like MongoDB or Couchbase. AWS has partnered with MongoDB which provides support and training for customers running their products on Amazon EC2 and Amazon EBS.
MongoDB is an open source, high performance document-oriented database which powers big data as the leading NoSQL database.
Here is a great presentation from MongoDB World on running high performance MongoDB instances on Amazon EC2