No matter how big your bookshelf, there will inevitably come a time when you run out of shelf space. On that day, you should look at this Invisible bookshelf, which will leave your books hanging on any wall in your house.
Unlike other invisible bookshelves we've seen, this version allows you to store your books vertically in a row. As Latestbuy describes on its product page:
How does the magic happen? It’s so wonderfully simple! It features an aluminium extrusion that acts as a bracket which you screw to the wall, and then a polypropylene combed strip that grips your paperback’s cover and pages – you simply tap your book against the comb to make it grip, and to remove it just pull gently and the combs release.
You can grab the invisible bookshelf for $30, which is significantly cheaper than the hundreds of dollars you're likely to fork over for a nice wooden bookshelf any day...