[tuvix]

Built an atari punk console using these with my late father. Still have it hanging on my wall in a shadow box.

[swed420]

I recently dug one out to use as a hardware shutdown timer to power off an rpi's PSU once it has presumably halted without having to resort to a dedicated MCU for the task.

[myself248]

My favorite 555 use was as a one-shot to power off a NIC after using its wake-on-LAN signal to reset a hung motherboard:

https://www.i3detroit.org/reset-on-lan-an-ethernet-aware-rem...