AddThis is a social bookmarking service that can be integrated into a website with the use of a web widget.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Sumo is a plugin offering set of marketing tools to automate a website's growth. These tools help drive extra traffic, engage visitors, increase email subscribers and build community.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.