Yes, you can definately get a cool tattoo along your ribs. There is one important thing to keep in mind before starting tattoo art on your ribs. Tattoos over bones can be very painful. You may want to break up the art into several sessions.
Yes, you can get a tattoo on the side of your ribs. It might be especially painful if you are skinny because it will be close to bones. Make sure you consider how your body might stretch and change when you decide a location.