I guess it depends what age and why they are in.
Our local soft play area are donating new toys to the hospitals play room. And our local bliss team are doing neonatal christmas bags for babies and parents on NICU. Including mini shower gel/soap, knitted small hat, a mini notepad and pen, mints, hand sanitizer, small Lindt chocolate, baby's 1st Christmas bauble, and a few other things on the list I can't remember. Everyone is donating certain things.
I think for slightly older children activity books and crayons should go down well to pass time, I bet they get bored x