Equally, you can charge businesses to ‘claim’ their listing, a method used by many large directory sites like Google Business and Yelp. This involves companies paying to upgrade their listing and adding information such as their web address, social media links, images, and more. Other revenue streams include charging for ad space, adding affiliate links and even charging for services and products on your directory site.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.