Hi E.,
I'm so sorry to hear about your friend's loss. My husband and I had a daughter Faith who was stillborn in March of 2005. It was probably the hardest and saddest thing I've ever gone through in my life.
I know everyone handles these types of losses differently so it's important to keep your eyes and ears open when you're visiting. If your friend seems open to talking about it, be sure to let her know you're there to listen. Encourage her to share her feelings no matter how she's feeling. I was talking to a friend of mine who also lost a baby in the third trimester a month after I did and we had some pretty bizarre thoughts and feelings and were ashamed to share them (we both thought we were crazy). But once we did it was such a burden off our shoulders. And let her know you're ok with just sitting there and being with her if she just wants/needs to cry. Offer extra long hugs, too. Those were always very comforting to me.
But if she seems closed off about it don't be afraid to talk about something unrelated to her situation. I found sometimes it was nice to talk about other things to get my mind off of it for a little while. Just try not to babble on just to fill up empty air space though too. I know it seems like a fine line, but this is a confusing time so it is going to be hard. Sometimes I didn't even know what I wanted. It's like you want to talk about it, but you also sometimes don't want to cry anymore.
Some things that I still remember receiving during our time of loss were the people who brought us meals. One friend just brought us a bunch of household supplies which was great (toilet paper, cleaners, kleenex, etc.) I'm not sure how close you are with your friend, but coming over and just saying "I'm going to do a load of laundry or dishes" was great too. She'll tell you if she doesn't want you to do those things, but even if you make an offer I guarantee she won't ask.
If you'd like to get her a gift I think one of my favorites was a tree. Three family friends went in together to get Faith a tree at my grandfather's park (through the park district). It's right near a playground and now that we have a 6 month old it's really special to be able to take him to his sister and great grandfather's park to play. I think that was a great memorial. (I have pictures of it here: http://hackbarth.smugmug.com/gallery/701893#30593996)
Lastly I found it really helpful to talk to other women who had been through what I'd been through. I don't know why women have to lose their babies, but I do know that God has a plan for everything. ("For I know the plans I have for you," declares the Lord, "plans to prosper you and not to harm you, plans to give you hope and a future." Jeremiah 29:11). And I know that part of God's plan for me is to be a resource for other women who are suffering through loss. So if your friend would like someone to talk to please feel free to pass on my information to her. My email address is ____@____.com you'd like my phone number please email me.
God bless you E.! I'll be praying for you and your friend in this time.
L.