Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Font Awesome is a font and icon toolkit based on CSS and Less.
jQuery is a JavaScript library which is a free, open-source software designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
A modest JavaScript framework for the HTML you already have.