Figure 14.5 Delicious.com, a bookmarking service.
Digg (www.digg.com) and Reddit (www.reddit.com) are sites where users
submit content which other users can then vote on. Popularity, based on votes,
moves the submitted content up and down lists which are available on these
sites. Submitting and voting requires registration, but there are many, many
people who visit these sites to get an overview of content that is “hot”. In fact,
in early 2011, Digg was at 135 in the Alexa rankings, with Reddit just behind at
139.