Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
EC-CUBE is an open source package used to build ecommerce sites.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Typekit is an online service which offers a subscription library of fonts.