For more information StumbleUpon is an Internet community that allows its users to discover and rate Web pages, photos, and videos,that many of us are always looking forward to. Apart from what yere said, StumbleUpon also allows its users to indicate their interests from a list of nearly 500 topics to produce relevant content for themand also there is one-click blogging built in as well which makes it full of advantages.
Another interesting feature is the way this works. This community uses collaborative filtering,which is an automated process where human opinions is combined with machine learning of personal preference, to create virtual communities of like-minded Web surfers. It was founded in december 2001 and in july,2006 it already had 1 million users !!
Though purchased by eBay in 2007,it is an independent company again.