Apache jclouds is an open-source framework that helps you get started in the cloud and reuse your Java development skills. Our API allows you to freedom to use portable abstractions or cloud-specific features. We support many clouds including Amazon, Azure, Rackspace, and VMWare.
fog is the Ruby cloud computing library.
The quick and dirty, top to bottom:
Collections provide a simplified interface, making clouds easier to work with and switch between.
Requests allow power users to get the most out of the features of each individual cloud.
Mocks make testing and integrating a breeze.