I did some research on what makes sites “sticky” and wanted to share some tidbits.

People repeatedly return to sticky sites because they’re popular, memorable and inspire action; popularity is obviously a function of being memorable and inspiring someone to act.

1. Clear value: there’s an understandable value to be obtained for the user, whether the site is being visited for task-oriented or experiential purposes
2. Customization / personalization: providing status, uniqueness and utility
3. Community formation: connection to real-world interactions, feelings of exclusivity and privacy, etc.
   
4. Front-load the community with influencers who are talkative and come from a wide range of backgrounds
5. Sense of comfort and inclusion within the site and community, with the knowledge or demonstrated evidence that information is protected from malicious usage on behalf of others or the site operator
6. Dynamic content: if nothing changes, there’s no reason to return
7. Peer pressure / herd behavior
8. Straightforward: easy-to-use, simple design that’s attractive to most of the user base and target audience

Research also indicates that for some sites, stickiness causes a reduction in pageviews and navigation depth, while visit duration may remain constant.  In other words, repeat visits to a site may reduce pageviews but have no effect on pageview duration.  This occurs because users of a site tend to remember where to go and focus only on the features that appeal to them.