I don't think you can go wrong with practical gifts, they are always well received. Claire we do the same!
*I usually buy 2 nice white towels and have the baby name embroidered, or I will buy one towel and one nice big cotton wrap and do the same with both.
*A few new season appropriate sized clothes are always good. Even though I had 2 boys, Ethan was born in Summer, then Lucas in the Winter, however we had a big crossover of sizes. Pumpkin Patch online have a good clearance on atm with free postage till the end of the month so you could pick up a bargain wrap, new little socks and some cheap outfits / bodysuits.
*New cot sheets, again something she will probably have, but worn from the toddler, however always nice to have a few new things for bubs.
*A few new bed time books. By the time Lucas came around 18mths after Ethan books mostly had ends chewed off, or ripped off. Do an order through the B00k Depository, will save you a bundle.
* New change mat cover. Sounds boring, but again perhaps existing ones are well worn. I buy these (nr bottom of page) they are so soft: http://www.kidsline.com.au/accessories.html
I can't think of anything that really stood out that Lucas got, actually he probably about 1/3 of the gifts Ethan did, not to mention cards.