Just read an amazing article on how you can profit from content marketing
The one section that caught my eye was holding a treasure hunt on your site. Your readers go searching for puzzle pieces on your site and fellow blogger sites and once a reader find all the puzzle pieces they win the prize and best of all it's some valuable piece of content or software.
I own resale and distribution rights to 30 gigs of digital products so the prize wouldn't cost anything. Great idea.