We like to use bookends for both their original purpose (holding books up) and for adding some visual interest in preventing the "wall-o-books" look that can sometime happen with large bookcases. We recently acquired some dog-shaped vintage bookends that we loved, but were a little too classic for our taste. Our quick fix? A few coats of a bright colored spray paint left us with totally fresh feeling pieces.
We have an arsenal of spray paints on hand, but it's a good idea to make sure the one you're using is suited for the material you're painting, in our case metal. There are also several finishes of spray paint available, so make sure you get one with the finish you're going for.