If you have a couple of older chairs collecting dust around the house and aren't in need of a bench then this project might be the one for you. Someone turned this old chair into a shelf by cutting off the back and seat and then screwing them together to create a shelf. The hardest part about this project would simply be to make sure that your cut is even the entire way through.
However, once that's done it's just a matter of screwing everything together. You might also want to make sure the chair you choose has an interesting design and woodwork on the back.