Selling custom engaging website using absolutely free opensource resources.
The concept is pretty simple,
1. Users earns bitcoins (can be any other currency too) when they visit your pages, posts, products, etc.
2. The User can purchase products from the website using the earned Bitcoins.
How does the webmaster earn?
1. You earn money from adsense or other ads
2. With your earnings, you giveaway items.
Fully built in WordPress using free plugins and themes.
You can see a working demo at
www.shopfree.ga(Note: I have used a premium theme and a premium slider plugin for demo purpose. Can be built with 100% free themes. Have used a free domain and free hosting)