um... clothes, toiletries, baby's clothes? trust me, you'll want a shower and those hospital gowns are not comfortable!
i'm sure there's a list somewhere but this is what i brought-
pajamas
fluffy socks x2
going home outfit (something big and comfy, you will not fit in your pre-preg clothes yet)
hairbrush
deodorant!
shampoo, conditioner, body wash (some hospitals provide this stuff)
makeup (it felt good to pretty myself up on the last day)
chapstick
my pillow
for baby i packed-
2 onesies
2 outfits for going home (in case he soiled one)
diapers (the hospital provided them, i brought a couple just in case)
pacifier
hat
blanket
basically pack for yourself like you would for a weekend away. if you plan on breastfeeding pack nursing bras and easy access pajamas.