You have heard in internet business content is king. What come after the content in internet business then?
The answer would be the community (loyal visitors that keep coming back and participate).
To come out with a successful website, you need both content and community. To make it even successful, you need to educate the community to create content on your website. This is what big websites do. For example youtube.com, wikipedia.org, facebook.com, digg.com, rapidshare.com and many more.
If the community do not create the content, you need to find other means of adding massive contents on your site as strong reasons for people to come back. This model used by google and other search engines that use so called crawler to go and bring back data from millions of websites on the net.
So always remember to create a successful website you need CONTENT + COMMUNITY.