ComScore Media Metrix reports through eMarketer that sites based on user-generated content are very sticky in the UK. Wikipedia, MySpace, Piczo, YouTube and Bebo are mentioned in the article. These sites “generated an average of 4.2 usage days and 79.9 minutes per visitor, according to comScore. By comparison, sites in the top 50 that were not based on UGC saw far less usage. Visitors went to these sites an average of 3.5 days and spent an average of 33 minutes.”
What it means: if you want deeper relationships with your users, give them more control over your site.