A social bookmarking website that was established in December 2001 by Garrett Camp, Geoff Smith, Justin LaFrance, and Eric Boyd. Stumbleupon or SU for short allows its users to bookmark web pages, comment on them and share them with other users. You can find all different kinds of content on there, but generally speaking, SU users like interesting or bizarre stuff and beautiful pictures, images etc. According to its homepage Stumbleupon has over 8 million users and currently, its Alexa traffic rank is inside the top 400. Joining the site is really easy, just click on the sign up now button, install their toolbar and start stumbling.
