My house is pretty small so i try to maximise all the spaces i can so we can store more of our things and not feel too cluttered. I needed a tall narrow bookcase and so i found the good old Billy bookcase from Ikea and decided to add a bit of detail to its plain white shelves.
I simply stuck fabric to the backing panel using double sided tape before i placed the shelves in.
It was a little tricky to get the cut exactly right so if you are going to try it out i would suggest cutting some cardboard the same size at the backing piece and them covering that in fabric and simply placing it in before you mount the shelves. It's easy to just remove the fabric when you get sick of it and go with a whole new look. You could also easily use wrapping paper, wall paper or stencil art to achieve a similar effect.
Other items on the shelf :: Yellow vase from Freedom / Owl from Bed Bath n Table / Blue vase from Ikea