Lots. I have a very poor memory for many things. Here is a list of most of my current lists: errands to run, things to buy, music I want to remind myself to look up later and that I can’t Shazam (classical pieces, mostly), movies, TV, short stories, wines, visual art, articles, and comics I notice or that people tell me to check out (I keep my book list by downloading ebook samples on Kindle), words I have looked up, gifts it occurs to me to get for people at their next birthday or holiday, stuff I still need in order to fully outfit my boat, the license plates and descriptions of the parking lot scammers I have reported to the police (quite a few), names of hospital staff who cared for my grandma and who I need to get chocolates and thank-you cards for, possible wedding locations, tentative wedding party list, things to remember to tell my therapist this week, schools I’m going to apply to next year, my extremely detailed camping list, kayaking list, kayak-camping list, and cabin list, things to yard sale when it gets warmer, my 56 favoritest movies (made it just for fun one day, to see how many I could write down without thinking about it), and things my grandma gave me (to help keep track of her estate).
I keep all my lists on my iPhone because I lose sticky notes almost immediately, and because I like to have them at hand for when I need them. Before cell phones came around I kept lists on my hands and arms, in pen, and refreshed them when the markings got faint from washing. My parents hated it.
I delete the everyday ones or errands and such when I complete them, but not the ones that contain info I like to use for reference. Lists of media to pursue grow and shrink as I follow up with them, but never disappear entirely. I also save some that are completely out of date, like questions I listed out to ask my vet. The pooch and I saw the vet ages ago, but I want to keep the list to remind myself what her issues were at the time.