Ways to discover stuff online without a search engine

What are some tools or methods (whether real, theoretical, academic, or otherwise) for discovering things on the Internet, as an alternative to using a search engine. I'm not focusing on practicality here, just looking some interesting and uncommon methods for getting novel results. I suspect there's a few specific to certain types of media.

The methods I'm aware of are:

- Recommendation engines (e.g. Youtube, most social media feeds)

- Organic / constructed sequences of data (e.g. a playlist, or sorted lists using some measurement like price)

- Non-text search (e.g. search via image, sound, or geolocation)

- Stochastic (e.g. guessing a domain name, or entering some random text into a search engine and skipping 100 first suggestions)

- Automatic link traversal (e.g. a web crawler algorithm)

- Private sharing (e.g. sending a link in an email)

- Public sharing (e.g. web portal, or blogroll)

- Hybrid (e.g. algorithmic search engine results, news aggregators)

But what am I missing?