I'm a librarian who loves anime, manga, and reading a wide variety of genres.
This year I restarted my shelf space project, which was designed to force me to keep track of the physical space taken up by the stuff I acquire vs. the physical space freed up when I offload things (usually either donating or selling them). Ideally, I should offload more inches than I acquire.
Yeah, that's not going so well. I just looked at the numbers, and so far I've acquired 12.03 inches more than I've offloaded.
Anyway, last year I kept track of everything in an adorable cat-themed journal, but I couldn't seem to keep it up for more than a couple months. This year I'm using LibraryThing for everything, and it seems to be working out better for me.