I lost a ds at 24weeks last year (next week). Generally friends and family were very kind, but no one really understood what it was like. I felt so alone despite having such wonderful care and support.
I found comfort in being able to talk about my baby as if he was "real", some people's palatitudes and cliches were particularly hurtful - and included stupid things like "You can always try again" or "I understand how you feel - I miscarried at 6 wks!!" "You wouldn't want a disabled/deformed baby to tie you down for life" some people even said "You could always borrow my baby for the afternoon" DOH!!!!! I appreciated when friends didn't bring their children especially babies around to see me for the first couple of months.
Friends became strangers and strangers became friends. Just be there for your friend, allow her time and space to grieve in her own way.
My house looked like a funeral parlour for the first few months, not to seem ungrateful but I would have liked people to donate money to a charity/local church in memory of my baby rather than send flowers. I don't know your friend, but perhaps you could ask her what she would like if you we're particularly close? Whatever gesture you make, I am sure that she will appreciate it. Its the people who ignored my grief, who didn't acknowledge my pain who really hurt my feelings. However I was also surprised and moved by the love and support of other people who I didn't know very well. I had lovely gifts - from angel figurines, prayer cards, and a beautiful scented candle which I light on days when I am feeling particularly sad.
Wesley Owen (a chain of Christian Book Shops) have lovely cards "On the loss of your baby" and there are several charities that can offer support: Tommy's Baby Charity, www.arc-uk.org, and in most local areas there's a branch of the Miscarriage Support Association, I think somebody has already mentioned sands, and there's the Babloss charity too who hold various events and memorials throughout the year.
One thing that I didn't appreciate was a "do gooding friend" who went on ivillage and posted a hurtful thread, telling people that she felt that I wasn't coping 3 months on, and that I should snap out of my grief and be happy for her now that she was pregnant. Be careful what you write about on this internet - it's a dangerous place at times!