One person’s junk is another person’s treasure. Freecycle is a group of people who give away things they no longer want to other members of the group. There is a Chicago Freecycle group that some people may find useful. Personally, I found this site too restrictive for the occasional trade.
They also send a lot of emails, so this site may only be useful for people who have a lot of things to give away and who expect to get a lot in return. (Again, meet in public places since books are easily transported). But there are enough people who love this group, so just because it didn’t work out for me doesn’t mean it won’t work out for you. If you like this site, you can trade more than just books.