I just found the most fascinating thing while tidying in the bedroom.
A chart, made by me in 1987, of my friends and acquaintances in high school, and who dated who, plus who had a crush on who.
The chart has different symbols for level of relationship (crush, one date, actually dating) and a method of showing what order the relationships happened in. It's fascinating, and I have absolutely no recollection of having made it, even though it was clearly made over a period of a year and with extensive commitment required.
Now I have to leaf through my other diaries and see if I made more of these. I guess this proves that I'm a natural information organizer. Or a psycho stalker.