[BjoernKW]

Apart from search engines and directories such as AltaVista and Yahoo and later obviously Google, bulletin board systems and Usenet were popular ways of getting and recommending new content on the Internet.

Another - somewhat quirky - concept was called 'webrings': https://en.wikipedia.org/wiki/Webring

These allowed websites with related or similar content (though the definition of what would be similar enough to qualify could vary quite a bit) to link to a 'next' and a 'previous' site. This obviously didn't scale to an exponentially growing web but it allowed for serendipitous content discovery, which could be quite delightful sometimes (and disturbing at other times).

[aurenen]

That's what I used, the webrings. I did a lot of link hopping from people's amateur sites because they all had "Links Out" pages, and there was a lot of website social circles that operated with message boards and webrings.