Arc is a peer-to-peer CDN that pays site owners for using it. Instead of expensive servers in distant datacenters, Arc's network is comprised of browsers.
Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
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.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Varnish is a reverse caching proxy.