AOL fan "mailing lists."
You become a fan of something, you make a literal mailing list that randos join, and everyone just shares their geekiness. There would even be categories in a lot of those mailing lists, like sharing fanart, sharing music, trivia, quotes, character spotlights, etc. Some would even edit music videos and share them ... And of course they would take hours to download back then. lol.
I ran a few Sailor Moon fan mailing lists back in the day until I lost interest in doing it and "retired" once I started high school. While I was doing it though, I had a great time. lol.
Keep in mind that these mailing lists were a big deal among anime fandoms because these took place during a time where accessibility of anime was still quite limited (especially if you were a Sailor Moon fan). It blew my mind discovering that there were other Sailor Guardians (Neptune, Uranus, Pluto, and Saturn) on the internet because those episodes took several years to come to the United States.