Glow sticks in the pool, great for night swimming! Not sure this would be the best idea for a big in ground pool (would probably take a couple hundred sticks), but would definitely be cool in a kid pool or an above ground pool!
It is a great idea if you have a stairway or long hallway. I have one whole wall of pictures of my family in my livingroom like this above the piano. Dream Home,For the Home,Home Sweet Home,There's No Place