Example 1: Apple App Store I have a simple app for converting numbers to English&Chinese. With zero ad money spent, it has ~10 downloads per day. Not a lot, but that's something. As a result, the app generates ~20USD revenue per month. Note that the same app has only 1-2 download per day in the Play Store.

Example 2: Youtube I once tried posting football highlight videos on a new youtube account (0 subscribers). Most often a video gets <10 views. But sometimes with the right keywords and timing, a video can have several thousand views.

Bad Example: Web? I made several simple sites. Apart from the week I post them on HN, they have basically zero traffic.

So any publishing platforms where you can have meaningful free organic traffic? It can be anything, e.g. Ebay, Steam, Twitch...