I use it for recipes! I use the iOS app Mela for recipe storage and it has a built-in RSS feed system to follow recipe blogs so you can easily add new recipes to your collection without having to visit all the sites separately.

If I have to pick an absolute favorite, old Neopets. Having the little webspaces there is what got me into coding as a kid and I ended up studying & working in IT.
If I can pick multiple, I'd also add phpbb forums of yore, game guides with ASCII art maps, Flash games, and MSN Messenger.

I use both but I'm terrible at taking meds regularly (ha, the irony!).
For losing track of time during meetings/focus sessions, I use a Time Timer to visually see time passing by/showing how much time is left.
For reminders, I use Due on iOS (+ Apple Watch) as it continues to send reminders until you do the thing and check it off.
For to-do lists, I use both paper planning with a bullet journal-esque notation as well as a whiteboard for "temporary" planning, like creating a prioritization matrix, as it allows me to shift things around more easily.