Open source, development SaaS, and .Net

There are many SaaS startups and platforms available online to help with software development. Most target selling for enterprise development, but many of them support the open source community by being free for open source projects. Those hosted on github get special treatment because of the ease of integration through github's apis. I will take you on a tour of this brave new world, and how it fits in and around .Net projects compared to others platforms/languages (Node,Ruby,Python etc)