First 3 Months:
Aquarium Bouncy Seat - I've had too many bouncy seats, but this one is an all time favorite of all 3 of my kids and of friends. Bright, noisy, all the things you want to avoid, but that babies love!
Baby Bjorn - register for it, you'll like it. Other friends swear by the expensive Ergo carrier, if you think you will want to wear your baby for longer than 6-8 months, try it.
Snap & Go - Don't register for a travel system. All of the strollers that come with those are stinky. Instead, get this, it is all you need for the first few months. Once you figure out how often you use a stroller, where you go, what you need to carry - then go shopping for a stroller. You just don't know until you have the baby. You'll have plenty of gift card to use, or register for one of the more popular strollers and if you don't like it, exchange it.
* as I was getting the link I noticed that this is $60. Ouch. I got my single one for free from a friend, and was happy to shell out the $100 for the double. But, see if you can get this on craigslist. Your baby doesn't even touch it, so don't be all paranoid about putting your precious first born in a used one!
2-Way Swing - I never had this, but I wished I did. 2 of my 3 kids didn't like the swing, but when we visited people who had this one they loved to swing side to side. Get it. There are a few different varieties.
Car Seat Cover - for winter babies this is essential. If your baby will be older by winter, then get one of these. They also have bug nets that are good for you out doorsy types.
Pack & Play, Cradle, Bassinet - I like to have the baby sleep next to me for a while. The pack & play seems to have the most longeivity as you can use it for travel for up to 2 years. Most have a bassinet layer so the newborn can sleep up higher at your eye level (when in bed). Cradles and bassinets are lovely, especially if a family heirloom or borrowed.
Bath Sling - for the twins I had a baby tub and I hated storing it, filling it up, cleaning it, drying it, etc. For Tyler I got one of these and loved it. I washed him in the sink and later used this in the tub with the other monkeys on either side of him. Cheaper, smaller, and very comfy looking!
I didn't have a rocking chair or a glider, but boy would I have loved one!! The glider is so comfy to nurse in, rock in, read in...you name it. If I had lived in more than 750 sq feet with twins, I would have bought one :)
I didn't use bottles, so you'll have to look elsewhere for help on BPA free ones and bottle warmers. I have spent a lot of time nursing and highly recommend an electric pump. Makes life much easier. Also, look into one of these - love it! After much trial and error, I decided that the reusable breast pads are eco-friendlier and more comfy than the disposable ones. If you have any other breast feeding questions, ask away!
More installments to come - happy shopping!