A collection of the best open data sets and open-source tools for data science, wrapped in an easy-to-use REST/JSON API with command line, Python and Javascript interfaces. Available as a self-contained VM or EC2 AMI that you can deploy yourself.

It's essentially a specialized Linux distribution, with a lot of useful data software pre-installed and exposing a simple interface. For full documentation, see http://www.datasciencetoolkit.org/developerdocs.