I don't use the library any more. I keep books for far too long - it usually takes me a month or so to read a good book - and I was being hit by a lot of fines for, in essence, not racing through books. Then for the books that I'm really eager to read, well, having to wait a year to get a book just isn't my choice. I buy it. It's good for authors and bookstores.
I've also become very enthused about giving my books away. Any paperback fiction novel that I finish will usually quickly make its way to a new person either in person or via Bookmooch. I just don't have the space anymore, and I am less in love with books as physical objects than I used to be before I moved over here. I also feel that paperbacks have a limited lifespan and are best "used up" rather than being allowed to fall to pieces over the course of the years. A paperback that gets four reads has done pretty well in my book. So I don't lend much anymore; I give. It makes doing the accounting a lot easier.
I am a very good borrower, I think; I segregate borrowed books and always return them. Well, unless we stop talking and I move across the world, in which case I may still have that book about Benjamin Franklin and farting even though it still gives me a twinge of guilt when I see it on the bookshelf