eBay Partner Network is an online referral program where eBay pays commissions to referrers on sales generated by customers they’ve referred.
Google AdSense is a program run by Google through which website publishers serve advertisements that are targeted to the site content and audience.
Google Analytics is a free web analytics service that tracks and reports website traffic.
PHP is a general-purpose scripting language used for web development.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.