community building

In web 2.0, everyone touts that community is key.  Looking at Digg, I couldn't agree more.  It started as an interesting idea and now enjoys a bolstering community behind it.  While there are technologies that make websites technically superior to Digg, what many of these sites lack is community.  What I'm wondering though is that even though there are thousands of Digg clones out there, how did Reddit make it to the top?

Communities all start by having content that helps the individual.  Keeping the content fresh helps visitors come back for more.  As your community grows, add social networking/community aspects to make content more useful and interactions meaningful.  In Digg's case, as link submissions increased, the most interesting news became more valuable.  Other social features added include:
-commenting
-adding friends
-feeds to friends and users
-recognition for accomplishments by users
-community enforced policing

an interesting proposal I noticed was to buy parked domains that have a lot of traffic, add useful content, then add social stuff ( grab.com and deals.com and wikihow.com)

another play off this idea is to buy the traffic generators for myspace/youtube and direct it to the next myspace (that you created)