AddThis is a social bookmarking service that can be integrated into a website with the use of a web widget.
Amazon Advertising (formerly AMS or Amazon Marketing Services) is a service that works in a similar way to pay-per-click ads on Google.
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.
Varnish is a reverse caching proxy.