Nursery artwork is nice to have too! Children's books too. :) rather than a card, I asked people to bring a book and write their note in it. That way I build his library and my guests get to express their favorite book growing up!
Definitely ask for diapers, but make sure to mention different sizes so you dont get a bunch of newborns!
I ask for clothes because that is what people like/want to buy then I return it for the boring things on my list. Usually breastfeeding things people don't buy you.
You could request gift cards for use at a later time
You cant go wrong with diapers an wipes. Maybe a nice thermometer. Bath soap/lotion wash clothes socks ....