Congratulations!
I'm sure I'm forgetting a lot, but here's a short list:
* Frozen meals, lots of 'em. Make sure they include spinach, or something high in iron. It's normal to be a bit anemic for a while.
* Lanolin, which is a lifesaver for the early weeks of nursing.
* A water bottle, and easy access to filtered water if you use that. You'll need to stay hydrated.
* Maxi pads.
* Tucks. I did not have a good experience with frozen pads, but other people swear by them.
* Some people (not all) also need Preparation H for a short time postpartum.
* A portable changing pad or some kind of baby changing station RIGHT THERE, where you'll be most of the day. Just for the first few weeks, getting up from a sitting position, let alone going up and down stairs, is NOT fun. Then, one day, you'll wake up completely healed -- it's amazing.
* Changes of baby clothes, also set up right there.
* A diaper genie, and about a million baby clothes and a million diapers, respectively.
* TEN BILLION wipes, I swear. I still think wipes are the most useful invention ever, and my "baby" is 7!
* Music, reading material, and your phone (and charger). With the baby blues (a natural hormonal shift, which passes), it really helps to stay connected to the outside world.