It’s easier than ever to keep your members coming back. You just need to combine the best of human motivations with technology. If you get this right, you’re making your job much easier for yourself.
Put someone in charge every Friday to create a missing person’s list. Anyone can add people that haven’t posted in a while. Over the weekend it’s customary for members to message as many as possible to see how they’re doing.
Or add a “People who might find this interesting” option to every piece of user generated content. This lets the users select names of their friends and community members who they think will want to read and participate in this debate. Like a picture tag, it sends you an e-mail inviting you to participate.
Or create a program that ranks every member by number of posts or time spent on the site. Even better, by the number of karma points/votes their content has received. Every member is e-mailed their position at the end of the month.