My very first thing was automation of placing my journal entry to appropriate Google Drive folder. I write my brain dump/journal everyday in Google Docs, and if I just click "New document, it places it in the root GDrive folder, and I had to move it manually which I am to lazy to do it.
LLM helped me write a python script that searches the root folder, finds the right document (name is always the date of the day), and searches for the right folder in assigned Google Drive repository (and creates a yearly or monthly folder if a new month starts).
It also helped me create a yaml script for Github actions to trigger this once every day.
I felt like a magician. Since then I created second brain databases, internal index of valuable youtube videos, where I call the api to get transcripts and send it to llm, other note taking automations etc etc