Well, motivated by this thread, I bagged and boxed up 63 books and boxed sets, plus a mass of binders and folders of hardcopy campaign notes.
All that is left are 8 books, two boxed sets, a few maps, and a partial set of Harn setting books (the ones I don't have on pdf).
About half the remaining items are probably going to end up on the scrapheap too, but not today. It is amazing how much of the stuff I have thrown away was systems and settings I never used. More than a few books haven't been opened since before the last time I moved, in '94.
I kept a lot of notes from my earliest days of gaming; I started keeping everything on a computer in the late 80s, so past that date most of my campaign still exist on disk, although I've only gone back to that sort of material a couple times.