Advertising income
The original idea was simply to sell banner ad space on your website. "Give me $20 a month to display your 468x60 graphic." But that was last century and you pretty much did everything yourself.
- tracking clicks, views
- visitor counts, unique IP
- contacting new advertisers
- communicating with existing advertisers
- processing payments and handling refunds
- technical support and answering questions
Today you can still do everything...