I splurged years ago, about bought a $27 leather Dayrunner organizer (calendar, address book, memo pad, calendar, places for business cards, zippered pouch etc) thing which was quite extravagant for my age and wage, and have used the heck out of it since, and only have to buy calendar refills for it yearly, and the occasional memo pad refill. It is very low tech and not very exciting, but after all these years it is more or less an extension of my brain, and I'd be lost without it. I am sure I'd easily adapt to something higher tech, but I have my laptop for that, and the low tech one for out and about.
Baskets/storage bins