You could try Bookmooch Last time I was there, You get roughly a point for every book you upload for sharing to others. It's not like readitswapit where you have to have a book someone else wants before you take one of theirs. You just get say 10 points for uploading ten books and books cost maybe a point or two to mooch from someone else. So, without leaving your laptop you could have ordered 3 or four books by offering 10 to the site! Also, I have a few that I'm giving away. I can send them if you like :)
Bookmooch is a great resource if you go through books and usually get rid of them once you've finished. What it is is you get 1/10th of a point when you "list" a book you're willing to ship to a person who "mooches" it from you. You get 1 point for the book you send out. You then turn around and "mooch" from others. The site explains it way better, but I ran the gist of it here.
I only thought of it because I received over 800 books from 2007-now from there, and mailed out 400 of my own to others. Selection is limited to only what people list, but it's a valuable resource!
And yes, keep the kid's books you enjoy with your nephew for your later life possibilities. We had my oldest at 18 and had titles from my husband and myself's childhoods set and began picking up 1 book a month (Waldenbooks bookstores were great!)
Good luck and keep us updated on what you find!
This sounds really cool but they have no system in place to deal with people who borrow books and don't return them (or who return them in bad condition).
Overall I trust http://www.bookcrossing.com or http://www.bookmooch.com because they're quite well-established but they do slightly different things! So, yes. :) Thank you for sharing, OP!