  The social Web is transforming the way information is created and
distributed. Blog authoring tools enable users to publish content, while sites
such as Digg and Del.icio.us are used to distribute content to a wider
audience. With content fast becoming a commodity, interest in using social
networks to promote and find content has grown, both on the side of content
producers (viral marketing) and consumers (recommendation). Here we study the
role of social networks in promoting content on Digg, a social news aggregator
that allows users to submit links to and vote on news stories. Digg's goal is
to feature the most interesting stories on its front page, and it aggregates
opinions of its many users to identify them. Like other social networking
sites, Digg allows users to designate other users as ``friends'' and see what
stories they found interesting. We studied the spread of interest in news
stories submitted to Digg in June 2006. Our results suggest that pattern of the
spread of interest in a story on the network is indicative of how popular the
story will become. Stories that spread mainly outside of the submitter's
neighborhood go on to be very popular, while stories that spread mainly through
submitter's social neighborhood prove not to be very popular. This effect is
visible already in the early stages of voting, and one can make a prediction
about the potential audience of a story simply by analyzing where the initial
votes come from.
