Hi there,
If the NICU is near-by you could stop by with packed lunches for her. Some NICUs offer meal vouchers, but not all of them and hospital meals can get expensive after a while depending on where you are located. I know that when we went to CHOP in Philadelphia for one day, it cost us $18 just for cheeseburgers, fries, and 1 drink to split!!! Give her a journal type of notebook and tell her how important it is to write things down during the course of everyday. She may think that she'll remember everything from the NICU, but she won't. My daughter was in the NICU for 8 weeks and I have forgotten soo much! Also, tell her to document each day in pictures. She will want those down the road. If you want to make her a little 'survival kit', things to put in the kit would be bottled water (very important to stay hydrated if she is planning on pumping/BFing), the journal, a small pack of tissues, disposable camera (just in case she forgets her own camera), a beanie baby bear for the baby (it helps relating size of the baby in pictures and nurses will use it to help position the baby).
Other ways to help is to offer to clean her house a little...or even to make sure you go over to help her clean and such after baby comes home. Taking a preemie home is overwhelming. I've found that just calling and asking if you can go to help usually doesn't work. People, in general, don't like to accept help...especially new moms. So, call her and tell her you will be going to clean or to cook and give her a choice of times for you to come. "I'm going to come over and clean your kitchen and make you dinner, is 4 or 5 a better time??"
Another thought would be to make a little extra when you make your own dinner and freeze the extras for her and her husband. Frozen home-made meals are great for new moms in general, but they are soooo helpful for parents of a baby in the hospital or parents who are bringing home a preemie.
I'm sure you'll get some other thoughts from other moms on this board. :) ...and good for you for looking for a way to help her! :) That is AWESOME!