You could dedicate a zettelkasten as a sort of non-linear memoir. Most of our memories are about an event or a scene. You could use a zettelkasten to record one scene or memory from your life for each “slip” or card. These could later be assembled for publication if needs be, or left as vignettes for retrieval via cross indexing.
This is different from journaling, diaries or blogs which are all linear time-wise.
Example: My father, a child of the Great Depression, taught me, as a lad, to always check the coin returns on payphones for change left behind. I later did this when walking through a restaurant lobby and my mother and grandmother were appalled my grandfather was amused. Note: I made quite a bit of money in change over the years.