Here is a list (in no particular order) of the things I think of when I am asked the above-mentioned questions. I'll mention some of the bigger items at the end, since relatives, close friends, or a combination of gift cards usually buy those.
1. Diapers and wipes are a top priority, especially if planning to use disposable.
Sidenote: Did you know a newborn uses 10-15 diapers a day, sometimes more?!?! Be prepared!
2. If planning to nurse, I found the following items to be helpful: a nice pump, especially for working moms (I like Medela, the yellow brand); nursing pads (I like Lansinoh, the purple brand); milk storage bags (Lansinoh); an electric pump car charger if traveling a lot or pumping in the car often; a Boppy pillow; a nursing cover; and burp clothe (Gerber prefolds work well)
Sidenote: You can get a lot of supplies and samples you need only at first from the lactation consultant at the hospital.
3. A lot of people forget to register for medical/grooming stuff. Thankfully, some of my friends knew to get me them: pain/fever reducer, teething gel or tablets, diaper cream (a lot of people like Triple Paste), and gas drops. I did register for a health care set. The nail clippers, thermometer, and nasal aspirator were must-haves for us. I also registered for some sensitive baby body washes and lotions, just in case Joel was sensitive. The lavender baby lotion smells really good, too. While not a necessity, I splurged and put it on my registry. If having a summer baby, you might want to register for baby sunscreen. A humidifier could be a good gift, too.
4. I took some friends' advice on a stroller. I got a Snap-n-Go, which fits almost all car seat brands. It is much lighter than a travel system. Another thing to have with the car seat or stroller when out and about is a car seat cover. It helps keep light out and somewhat deters people from peeking at a sleeping baby.
5. Big swaddling blankets (mine shrunk and were too small after about three weeks)
Sidenote: Not all babies like being swaddled, but I am interested in trying a Woombie next time. Joel was able to get out of the Velro swaddlers fairly quickly.
6. A few fitted sheets and two mattress pad covers to alternate should do. Don't register for blankets. People enjoy making them as special gifts. We chose to get a mesh bumper (due to debate over bumper use), and have really liked it.
7. Back pack diaper bags and fold-up changing pads with a place to put wipes and diapers are super useful. Two shoulder straps are easier than one. The bag doesn't fall off when you bend over to pick other things up.
8. Register/buy things for a few months down the road. My friends will probably laugh at this, since I'm such a planner. The little things you need around five or six months add up, though. Trust me ... I'm there. I'd recommend registering for a few plastic bibs. You can wipe them down instead of washing them every time. Usually these are a little bigger, so you'll still need smaller cloth ones. Don't register for cloth bibs. People will give you these because they are cute! I'd also get spoons, sippy cups, a bottle brush, a squeezy spoon for travel (a food container with a spoon tip), and a freezer tray for homemade baby food. By the way, you don't need an expensive baby food maker. Regular blenders and choppers work fine. Last for this list, I'd register for a shopping cart seat cover with bumpers on the sides. I have recently found this helpful. I no longer have to take up half of the cart with the car seat. Plus, Joel really likes sitting up and seeing everything.
9. If you'd like to register/buy a bigger item, these are the things I found have most useful: crib, mattress, breastpump, glider/rocker, highchair, Pack-n-Play (for travel and hanging out with friends), and an infant car seat (we like our Chicco Key-fit). If I were to register again, I would also put a second stage car seat on the registry. They can be really expensive. (We're saving for that now.) We didn't buy a changing table. We just throw a changing mat, prefold cloth diaper, or my changing pad on the floor.
You might be asking where all of the other stuff is, so here is my humble opinion on that. Borrow swings, bouncy seats, Johnny Jump-ups, exersaucer, play yards, bassinets (unless using a Pack-n-play type thing), clothes, bottles, baby-wearing gear, and Bumbo seats. For a first baby, try these things out at a friend's house. See if your baby likes it. If not, don't buy one until the next kid comes around. You'll be glad you saved the space and used your gift cards for diapers. You really only need a few things to sit the baby in when you need a break. Having one of all of the above out isn't necessary. For instance, we have all of the above, except for a bassinet. We borrowed a Bumbo, got a used Johnny Jump-up after figuring out that he liked it, bought an exersaucer after trying it at a friend's house, and were given used bottles. We got the the swing, bouncy seat, and play yard at our shower, but borrowed them from friends to see if he liked them before opening them. We have clothes through size 4T from friends and relatives that are done having kids. Babies do need clothes to wear, but I wouldn't recommend registering for them. Most people aren't able to resist how cute they are, and throw an outfit in with a gift anyway. Buying gently used clothes at a consignment shop is a huge cost-saver, too. If you bought or were fortunate enough to be given all or most of the things above, let someone borrow yours to get it out of your house/storage for a while.
One last piece of advice: I would recommend having shower hosts ask for a book with a message inside, rather than cards.
