Paperclips
Yay I have paperclips! This is probably not nearly as exciting to everybody else as it is to me, but it means that now when a patron asks me, “hey do you have a paperclip I can use?” My response can now be, “Sure do, here ya go.” As opposed to my usual, “Sorry, I don’t. Check at the reference desk they might have one.” And beyond their use for patrons, paperclips come in handy to me too for things like holding my papers together, or making chains when I’m bored, or picking locks. So many uses!
General Lordisimo's Apocalypse 
I am fairly certain that a standard American paperclip weighs exactly 2 grams – in which case paperclips can be used as an extremely precise unit of measure… for drug dealers mostly, and OCD cyclists who obsessively weigh every single aftermarket bike component before a purchase.
Thanks to the metric system, one could infer that, weighing 70kgs would equal weighing 35,000 paperclips. (Hours of fun.)
Or maybe they’re 1 gram. I can’t recall.
I just checked, and the weight of a standard paerclip is exactly 1 gram. A 75kg man thus weighs 75,000 paperclips.
That’s a lot of paperclips.