I have one used bookstore that I still occasionally browse at, but in the end if I find something interesting I generally check out Amazon to see if it's available as an ebook.
My last holdout for paper books has been cookbooks, but I'm finding more and more of these available as ebooks and I expect eventually that path will be gone.
Last night was the first time in nearly a year that I purchased paper on Amazon (a couple of older homebrewing books still not available as ebooks). It'll probably be another year before I'm tempted again.