Among the many ways I am piercing together a dollar here and a dollar there is on Amazon, where I am selling off my unloved and unread and unplayed items in my library.
It's super easy. You sign up to be a seller, click SELL SHIT and enter in an ISBN and a brief description of the quality of the item you're holding. It sells, Amazon takes an unreasonable commission, but gives you a more-than-enough shipping credit to make up for it (I guess, if you consider a $1 shipping profit some amazing thing).
So far I've sold 8 items and had about $40 deposited into my bank account. The 8 items I sold cost about $3 to ship, so I've made a $16 profit, whoopitydo. It's about an extra $5 so if my math serves it's an estimate $250 extra annually.
So yeah, whoopee!