Clothes - look at Earlybirds They make clothes for babies from around 1kg+. They're not only gorgeous, they're structured so medical stuff can get around them. If you're crafty I have a pattern for prem bubs' smocks too.

If you're nearby you could make up a heap of frozen meals for them? Or get them a gift voucher for a restaurant close to the hospital bub's at so they can have a nice meal?