The Sierra Buddies run by the Sierra Club wanted an interactive space where students can discuss topics posted by the coordinators. We used IntenseDebate, a hosted commenting system from the makers of WordPress. It integrates into the blog seamlessly and has some nice social features, and easy to moderate from the admin side.
Students can sign in with Facebook (and other services like Twitter) which just made sense for the audience, and we really think it give an extra personal touch and removes barriers to interacting.
The other big thing was an ecological footprint calculator that was simple for youth and based on factors that they could affect in their lives. A few questions averaged over three days. Our friend Jessy Ouellette helped us make a custom WordPress plugin for the site. Neat!
Again, usability was really important here - couldn't have kids losing patience and leaving, needed it to span over three days but didn’t want anyone to have to create account or forgeting passwords. So how did we create the path of least resistance? The solution was just entering your email before starting. The system saves your results and the next time you’re back, enter your email and away you go.