cdnjs is a free distributed JS library delivery service.
Disqus is a worldwide blog comment hosting service for web sites and online communities that use a networked platform.
Fastly is a cloud computing services provider. Fastly's cloud platform provides a content delivery network, Internet security services, load balancing, and video & streaming services.
GitHub Pages is a static site hosting service.
Modernizr is a JavaScript library that detects the features available in a user's browser.
Varnish is a reverse caching proxy.