Hi R.,
Good question! I wish I'd known about mamasource when I first had my son!
Everyone's needs are different, but this is my two cents in the order that they occur to me:
1)Boppy pillow if you are going to nurse. I didn't use it when he was a tiny newborn, but once he gained some weight and length, it was irreplaceable. Also useful for propping them up on their tummies and sitting them up. My husband stole it to sleep on and I used it as the world's biggest "doughnut" cushion for hemorrhoid relief those first few days after birth!
2) Breast pump. You can rent one from the hospital. If you get help from WIC, they rent them out too.
3) Nail clippers. Their nails grow fast and are SHARP! Because I was really afraid to clip tiny nails -- baby gloves/mittens. They flail their hands and scratch their faces easily. The gloves prevent them from scratching themselves.
3) If you are breastfeeding, Lansinoh ointment for sore nipples. Also, breast pads are a necessity. I got disposable ones because I knew I wouldn't be up to washing reuseable ones.
4) Diapers and more diapers! Not a glamorous baby shower gift, but sooooo useful!!!!
5) If you want to co-sleep, a co-sleeper thing to attach to the side of your bed. I started my son out in his own crib and didn't start co-sleeping until he was about 4 months old. This time around I'm going to get a co-sleeper. I ended up co-sleeping with my son because I was so exhausted from working and getting up all night. It was easier to breastfeed and sleep.
6) For me, I loved having a rocking chair. I could sit there all day long on my doughnut rocking and soothing both my son and myself.
7) Soothing music to listen to. Even just music you like listening to. Just because it's a baby doesn't mean it can't get used to the music you like. I exposed my son to all kinds of music that I liked. So, CD player and music.
8) Night light. That way you don't wake the baby and anyone else by flipping on the lights, but you're not stumbling around blind during the night feedings and changings.
9) A baby swing really helped for those moments of inconsolable crying and those times when I just couldn't stand another minute of the crying and holding him. He fell asleep in it many a time.
10) A stroller so you can get out of the house. I personally got a travel system, which is a stroller and an infant carrier that attaches to a base in the car (baby carrier and car seat in one). Just so you know, the smaller they are, the more portable they are and the more places you can fit. The larger they are, the more stuff they can carry, but it's not so easy to go shopping (e.g., clothes shopping at the mall) with a huge system. The one I got is pretty big and I like it because my parents lived on a farm and that thing would handle almost any terrain. But it's a pain to use when shopping because it's so big. When the baby can sit up by themselves, you can get an umbrella stroller which is only $10-$20.
11) Diaper bag. Be careful what size you get. The larger you get, the more likely you are to fill it up and the heavier and more unwieldy it is. Get a medium size. They are extremely useful.
12) baby socks and hats to keep the little one warm
13) This should be #1 on the list. Enlist help from friends, family, and well wishers. I don't know what kind of support system you have, but if anyone offers to help, TAKE THEM UP ON IT. Giving birth is an amazing experience, but it's exhausting. Feeding the baby every two hours or so ROUND THE CLOCK is utterly exhausting. It feels like you haven't a second to yourself and that the baby constantly NEEDS you. You are, of course, ready and willing to be the provider, but you are so exhausted life is like living in a zombie twilight at first. Don't worry, it gets better over time. But the very beginning is exhausting, no two ways about it. So take measures to take care of yourself!!! I'll repeat that -- TAKE CARE OF YOURSELF! If you can, get people to make food to put in your refrigerator, get volunteers to do house work or run errands or watch your sleeping baby while you jump in the shower for a few minutes. This is where not having to go shopping for more diapers is extremely helpful.
Some things I found that I DIDN'T need, personally.
1) changing table. I always ended up changing him on the bed.
2) bath. I put a towel in a dishwasing tub. You don't even need soap or lotion when they are tiny. Just a soft wash rag or even just your hand. They don't get dirty or smelly when they are so small and new.
3) baby wipe warmers and things of that sort are a waste of money, in my opinion.
4) beware of clothes. To be honest, that's probably the bulk of what you are going to get from your baby shower, no matter what you register for. You will probably get tons of adorable outfits and blankets. I got so many blankets for my son that I still have drawers full of receiving blankets, afghans, and plushie blankets that have never been used.
Sorry this is so long, if you have read to the end :-) I remember vividly the confusion and excitement of being an first time mum and I hope this helps.
Congratulations and best wishes!