High-ticket consulting or coaching: You could sell your own high-ticket consulting or coaching products from your website. You'll still need a website, merchant account, sales funnel, lead magnet and many other items. But you can easily earn a substantial amount of money from each individual customer, making it well worth the arduous setup required.
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.