Noodles! They only last a summer if you keep them outside but EVERY one loves playing with/on them.
There is a floating cooler! (To lazy to google for link)
PLASTIC cups. You can get the ones that freeze to help keep it cold. NO glass anywhere near the pool!
A nice tray to help carry stuff out to the pool.
I would order your test kit when the gunite is shot so you can practice on your fill water so you know what you need to buy to help balance your water when you get plaster.
Oh and cards to write our invites on for you pool party!
Kim