One of my fellow freelancers, Jessica Mousseau of JM Writing, is giving away books and VHS that she doesn't want anymore. All you need to do is cover the cost of shipping.
If I weren't perpetually in the process of culling my own book collection, I'd take her up on it. You just can't beat free books!
As it is, though, I've run out of even overflow space: My books reside not only on bookshelves, but also boxes in storage and in stacks on the floor in front of said bookshelves. The library has become my best friend, not only because it's free, but also because I just don't have any more room for books I'll only read once.