Here are some elements which I think would really make these mini-sites work:

Single-issue. Deal with a few topics.  

Reference-friendly. Make your site more linkable. Cover an issue in full, through original content and external links.

Novelty/Simplicity. A single-page website work best. Use a clean, unique and topically relevant site designs will always help.

Viral components. To make people spread the word, encourage them by providing sharing options like an email-a-friend feature or link-to-me banners. Favorite tools that marketers have used include quizzes, videos and polls. Anything interactive.

Link. Use a link to an email list or master site