Just a little recent update to J's bedroom: we put up two RIBBA picture ledges for some book storage.
I am finding these are great for paperbacks as it helps remind your children of the books they have (since paperbacks have such a thin spine, it's easy to overlook them on the bookcase). Plus, I like seeing all the pretty book covers.
I just swap out the books every couple weeks or so, which usually results in our rediscovering a book we haven't read for a while.
These shelves come in two lengths: 45 inches and 21.5 inches. One thing I learned: the holes on the longer RIBBA shelves are spaced 16-inches apart, perfect for making sure that your shelves are screwed into the wall studs. However, the holes for the shorter RIBBA shelves are closer together (only 13-inches apart), which I think makes them harder to hang since you're only guaranteed to hit one stud. I was actually planning on placing the shelves end-to-end (one large and one short per row) to make two 5.5-foot ledges, but the spacing of the screw holes messed up my plan. If you are interested in buying these, I would advise measuring your wall and locating the studs before you go to IKEA; then just double check the spacing of the holes on the picture ledges before you buy!
I'm sure we'll find another use for the small shelves. At least at $15 for the 45-inch ledge and $10 for the 22-inch ledge, they're not going to break the bank.