I have to admit its going to be hard to do these list because DD1 and DD2 were totally different babies. What worked (and was a lifesaver for one) didn't work for the other at all.
Things i'm glad I bought:
bucket car seats- I rarely took them out of the car but when it was downpouring it was nice to be able to cover the carseat with a poncho and run for the apartment.. That way the girls didn't get wet (even though I got soaked!)
Carriers- with DD1 I didn't find a carrier I could use until she was 6 months but that thing was a lifesaver when she went through a "don't put me down or Ill scream" phase. With DD2 I had/have and used: a moby wrap (loved until around 5 months), a beco (my favorite for back carries), an ergo (best thing for DH, he would wear her all day except for feeds) and a mai tei (so sad this one tore really badly while we were hiking once :()
outfits- I know most people just keep their children in onesies/sleepers but I never did. For some reason I never felt like we were "starting our day" until we were all dressed. So, each morning the girls got dressed.. and then changed because they had really horrible spit up. We went through anywhere between 7-12 outfits a day because of spit up and explosive diapers.
With DD1- a swing, we moved from California to Japan when she was 4 months old so she spent time in the swing during packing although not much after we moved (she was to big/old for it when it finally got to Japan).
A breast friend nursing pillow- I had a really bad epidural experience with DD1 that caused some lasting back damage. This pillow literally is the only reason I was able to nurse, it supported my back enough where it wasn't extremely painful for me to nurse
a breast pump- I went back to work when DD1 was 6 weeks old, unfortunately she wouldn't take a bottle and that caused a lot of issues. My second ended up in the NICU and refused to nurse in the beginning. I got better results pumping with my double pump than with the hospital pumps! Luckily I was able to get her on the breast within 12 hours of her coming home and after a week I stopped pumping (and had a great little stash built up)
a bunch of blankets for DD1- she would only sleep swaddled for the first 4-5 months. If she wasn't swaddled she would be up every 5-10 minutes all night long.
An exerciser with DD1- she LOVED this thing and played with it happily every night for months while I cooked dinner.
burp rags- both girls spit up a TON, it was nice having something over my shoulder to at least catch some of it!
bouncy seats- I actually have 2, one in each bathroom. It was the only way I got to shower/go to the bathroom with DD2. DD1 would take off with her if she wasn't in the same room as I was so she had to go into the bouncy seat whenever I wanted to shower or go to the restroom.
A double jogging stroller and a double stroller- I know its controversial on this board but when DH is gone its the only way I can get out of the house. There is no way I can wear one and chase the other. Specially since DD1 is always wanting to be carried if we don't have the stroller with us. I specially can't carry both now that they weight over 70lbs combined and Im 33 weeks pregnant. The joggling stroller is to big for our trunk BUT its great for the long walks we like to take as a family
Things I wish I'd bought:
A carrier earlier with DD1. She loved being in a carrier, would have saved my back/arms.
Books earlier. I was told with my first it was useless to have children books before they started to read and for some odd reason I listed to that advice. Well DD1 LOVED to be read to from a really early age. I use to read Jane Austin and Shakespeare to her when she was a newborn because it would calm her when she was crying. Needless to say I ended up having to invest in some children books when she was a couple of months old. Now if she isn't bringing me a book to read her sister is.
breast pads BEFORE the baby came. I didn't think I would need them right away, my milk came in at 2 days post partum and I leaked heavily. They ended up tracking some down for me at the hospital because I was leaking so bad it was soaking my shirt
A decent diaper bag instead of the cheap one. It was a pain in the bottom black hole but having two in diapers a purse just didn't cut it. DH splurged on me this time and got me the bag Ive been wanting, can't wait to try it out!
A hook on high chair for our dining room chairs earlier than I did. The girls both liked to sit and be with us but it took a while for me to figure it out.. It made life a ton easier when we got one of those chairs and hooked it up. Happy baby, fed parents, happy family.
Things I'm happy I DIDN'T waste my money on:
wipes warmer- never got cold enough to need it. I live in a warm environment with a heater though. Im sure if I lived in a colder place it would be different.
A swing with DD2- DD1's swing was bought used and died before DD2 came around. We decided to wait to get one, tried one of my friends swings out when she was a newborn and she screamed her head off as soon as it was turned on.
tons of toddler spoons/forks. Neither girl would use them so I was glad I only had what was given to us.
A baby gate, my daughter could climb our neighbors gate by 7 months so it would have been a total waste AND been dangerous. I know some people its a necessity but I don't have stairs at our apartment and my daughter is a bit of a monkey.
bottle sterilizer- I was told I "had to" have one never bought one. good thing because I don't think I would have ever used it.
special soaps/powders for the baby- my first didn't have a soap bath (other than at the hospital) until she was probably 7ish months old. Second was around 4ish months old when she had a soap bath. Both times I just the aveeno I had for me on them.
Things I totally wasted money on..
sippy cups! neither girl would use them
expensive bottles for my first. I tried every bottle out there on her and she wouldn't take a single one.
A crib/changing table- it was bought for us BUT it was totally a waste of money/space
a bassinet- I was so convinced that co-sleeping was dangerous that I REFUSED to allow my baby to sleep with me.. just wasn't happening.. until neither of us slept the first two weeks and I ended up falling asleep nursing her one night. After one decent night of sleep DH realized how much better my attitude was/how I felt was that he started insisting we sleep with her in our bed with us.
baby tub with my first-Total waste, used once. It was to much of a pain.
baby monitor, never used then it turns out it was the wrong frequency to use over here so we couldn't use it. Never would have needed it anyway since our apartments have always been small enough where I could hear them all the time.
A jumperoo with DD2- figured it would work just as well as the exerciser (which I had loaned out to a "friend" and they decided to move back to the states with it ughs!). She didn't like it, I didn't like it and DD1 thought it was hurting her whenever she was in it so it was never used
A diaper genie with my first- was told it was the best piece of equipment you could have and since I have a very sensitive nose I figured Id give it a try.. yea it didn't keep the smell away and it as a waste of money.
Cheap plastic baby toys- I didn't want to "deprive" DD1 by not having toys for her. yea not only did she NOT play with them but I ended up giving them away or throwing them out (quite a few ended up recalled) so it was a total waste of money.
Any decorations for a nursery. The room was never slept in. Ended up being a total waste
swaddling blankets for DD2- She wouldn't sleep swaddled and screamed if you swaddled her. She doesn't like being confined, she still won't even sleep with a blanket covering her.
Baby memory books- this time Im just doing a journal and Im finding it a lot easier not to have to find the "special spaces" to fill in. It might actually get done this way!
Baby play mat things- you know the ones with the arch of toys above them. Both girls were scared by them so they ended up being used without the arch as a glorified baby blanket
Shoes for a baby that isn't walking
pack and play--- twice-- I didn't use it the first time, got rid of it then DH convinced me to rebuy it.. Didn't use it the second time, got rid of it. He tried to convince me to get a third and I refused.
A baby food "kit" to make and freeze baby food- both girls went right from Exclusively breast feeding to cut up veggies.
One of those big stand alone baby high chairs. Totally worthless IMO.
Im sure there is more I just can't think of what else.