If you are one of those rare few that like to be prepared ahead of time, here is a list of things you will more than likely need for your time in the hospital.

An Infant Seat
A going home outfit (for baby)
A receiving blanket
A few newborn diapers (if you are planning to use cloth, be sure to pack everything you will need for using cloth diapers, pins, velcro wraps, etc.)
A pair of socks or booties
A cap

A going home outfit (for mom).  Make sure it is roomy and easy to get into.  Probably will be some of your maternity clothes.
A flat pair of shoes
For breastfeeding moms, be sure to pakc a nursing bra and breast pads.
Sanitary napkins and some maternity underwear.  The hospital will provide some sanitary napkins and some net underwear, but it is always better to be safe than sorry.
Bathrobe
Nightgown
Slippers
A couple of pairs of socks (don't pack anything too fancy as you will more than likely stain your clothes during labor and right after delivery)
Toothbrush
Toothpaste
Shampoo
Lotion
Soap
Hairbrush
Deodorant
Make up
If you wear contacts, be sure to pack everything needed to care for them as well.
If you and hubby enjoy reading, you might want to pack some reading material.
Address book with lots of change or a pre paid phone card for calling your friends and family
A camera/video camera with extra rolls of film and batteries