MongoDB - MongoDB (from "humongous") is a scalable, high-performance NoSQL database.
Aerospike - Aerospike is a high-performing NoSQL database supporting high transaction volumes with low latency.
Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
CouchDB - HTTP + JSON document database with Map Reduce views and peer-based replication
Cloudify - Accelerating Software Development & Deployment
RethinkDB - The open-source database for the realtime web