Reporter e-mail addresses. Every bylined story should have the writer's e-mail address to facilitate reader feedback. I'll give you a bonus interactivity point if your site also includes writer biographies so that readers can get to know your staff better. Article feedback mechanism. The truly interactive site will solicit reader comments at the end of every story.
Readers use a Web form to write comments which are posted at the end of each article.
Personal Web pages. Now we're getting to the good stuff. The best interactive sites that I've seen allow site users to create their own Web pages, hosted by the news site. A boats page features user-created pages with photos of and text about private boats. A cars page on Sunline features pages where users have even contributed recordings of their autos' engine sounds.