MongoDB - MongoDB (from "humongous") is a scalable, high-performance NoSQL database.
Amazon EC2 - Amazon Web Services offers reliable, scalable, and inexpensive cloud computing services. Free to join, pay only for what you use.
Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
Microsoft Azure - Windows Azure and SQL Azure enable you to build, host and scale applications in Microsoft datacenters.
ArangoDB - A distributed open-source database with a flexible data model for documents, graphs, and key-values.
DigitalOcean - Simplifying cloud hosting. Deploy an SSD cloud server in 55 seconds.