My answer relates to a newborn - cause there are different "needs" now my DS is a big boy...

Couldn't do without:
1. muslin wraps in 120cm square
2. change table with slide out baby bath
3. sunshade window covers for car
4. play gym/activity centre with removable base for machine washing
5. fisher price aquarium cot toy

We didn't use:
1. baby monitor (depends on particular layout of house I guess)
2. knitted things in small sizes - sooo not worth it when they wear it once and it needs handwashing!
3. soft toys - blahhhhh you'll receive sooooo many of them as presents no need to buy them yourself
4. rocker chair - DS never liked it so was a TOTAL waste of money and space for us
5. mittens