Must Haves:
The Fisher Price Healthy Seat Booster - with 3 kids in our family the exact same age, we have tried all different boosters and this is the best one. Also, I recommend skipping a traditional high chair, especially if you have a small dining area. you will not need it.. and the trays are huge and hard to clean. don't be lured in the by the reclining feature. if your baby needs to be reclined, he/she prob shouldn't be eating anyway. this FP seat is great for taking to restaurants or anywhere!
Sheet Savers - use them in the crib for spit up, etc. you just tie it to the crib slats, and replace it when dirty. get at least 2. much easier than pulling the sheet off.
car seats - be sure to register for the infant seat, and the next step convertible.
diapers, wipes, travel wipes case, safety swabs, baby wash.
Skip:
Exersaucer & Bumbo seat - borrow one. they are expensive, and you won't want to store them. baby only uses them for a short time anyway.
wipes warmer
toys, clothes, books - you will get these anyway, especially if you know and tell others what the baby is! with your registry, you'll want to encourage people to get the things your really need!
Bedding Set - Instead, register for the decor items separately. the set usually includes a bumper (which are not necessary, and are usually not recommended anymore), a crib sheet, a quilt (not useful since babies can't use blankets), and a dust ruffle. You can use other items to decorate, like a lamp, rug, wall hangings, etc. and save $150 - $200.
blankets - you will get a bunch from grannies who make them, and others anyway. the granny knitted/crocheted ones are great for baby when he graduates to a blanket, and the fleece/quilt ones are great for playing on the floor and in the carseat.