Not exactly free but I just joined book mooch to get rid of my huge pile of overflowing books in the last 10 years, I'm just keeping the ones that I actually refer to. I will be adding to my inventory all summer in hopes that someone else can get use out of the ones I no longer read. If you haven't heard of this site, check it out. You get points by sending books to other readers and if you want a book you "mooch" one from someone who is getting rid of it. With books having little value at resale, I thought this made more sense. Of course you have to pay postage to send out the book, but in return you don't pay postage when you request one. I'm hoping to "mooch" some good reference books this summer.
Lovingly,
The Writing NagLabels: free writing books, novel writing books