https://www.timeanddate.com/ is one I keep going back to. Lots of useful tools everywhere, for scheduling events across timezones, get the twilight time instead of sunset to plan activities in the evening, eclipses, moon phases and so much more!

https://www.thisiswhyimbroke.com/ Hard to find, mostly useless. Often times amazing stuff to waste your money on for a dopamine hit.

https://stilltasty.com/ Great little site to gauge when food goes bad.

https://privacyguides.org community is here: @privacyguides
https://f-droid.org (I use it solely to find FOSS android apps... Then i install the newly found app with Obtainium)

mynoise.net It's got a huge list of generators for all sorta of sounds, from soundscape and environmental noise like coffee shops, to musical instruments, to white/grey/pink noise, and all sort of other things.

There's nothing better for when my tinitis is acting up and I want to play some tonal drones, or I just want to get into a mood by mixing some Tibetan singing bowls and a rainforest, or maybe just play noise-blockers to help me focus.