There's a big pile of unwanted books next to my computer, and I have finally figured out what I'm going to do with them. No, I'm not going to give them to an op shop or sell them to a second-hand store. I'm not going to offer them to friends or give them away as pre-loved Christmas presents. What I am going to do is leave them in public places and hope that an interested party will pick them up. It's littering with altruistic intent, with the added geeky bonus of (possibly) being able to track whether somebody does indeed adopt them.
So if you are keen to nab some free books, you'd better sign up and watch for alerts in Melbourne's east.