For shampoo, give the Earth Bath products a sniff (especially the cherry puppy one!) if you have them in your area.
I like the suggestion of a first aid kit too, but as an alternative to Peroxide you can keep a pouch of sea salt on hand. It doesn't degrade, and it is safer than Peroxide. If you (God forbid) ever have to use it, just make sure to offer lots and lots and lots of water after doing so. People worry about using salt to induce vomiting because of the kidneys, but they really do IMMEDIATELY vomit it all up (err on the side of too much, rather than too little) and the few times in a dog's life you have to do it if at all, it isn't a real concern. People run into problems with salt when they're overly cautious, use too little, and the dog has salt in his system for a length of time.
What about
:
Pee pad holder
Blankets for laying in his crate, or a crate pad
Grooming kit... How will you do the puppy's nails? Also, a brush is nice for bonding, and getting him used to long coat care
Chew products - bully sticks, yams, duck feet, etc.
Harness, leash, collar with a bell
On my list, I also include specifically interactive treat dispensing games and puzzles. We clicker train, so we develop a thinking puppy. You may not wish to have these, but just in case, there you go.
Also remember to book his first puppy class if you're doing that, and his first vet appointment. It is easy to forget, and then you miss deadlines!
Have fun!