AddThis is a social bookmarking service that can be integrated into a website with the use of a web widget.
Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Vimeo is a video hosting, sharing and services platform. Vimeo operation an ad-free basis by providing subscription plans.