StumbleUpon Essential Basics, A Beginners Guide, by Ann Smarty, Search Engine Marketing Group (May 8)

Tells us a lot about Stumbleupon – such as – “StumbleUpon is based on the relevance mechanism: each member is categorized based on his interests – these interests are determined based on the preferences specified by him and also based on the member’s browsing behavior (topics of the articles the member usually stumbles and reviews).”