I've got 2 bags. One for labour, one for if we have to stay in hospital afterwards.
Labour bag has:
2 nighties (1 for labour, 1 to change into after I clean up afterwards)
Dressing gown
Slippers
Wash kit (everything travel-sized, new toothbrush etc)
Make up
Lip balm
Moisturiser
Hairbrush/hairbands
Knickers x2
Maternity pads
Vest & sleepsuit for the baby
Nappies x2
Towel
Flannels x2
Water/cereal bars
and stuck to the top of it is a list of things to remember as we leave -- car seat, phone, kindle, charger, camera.
In the 'after' bag:
Nightie
PJ bottoms/top
Nursing bra
Knickers x4
Maternity pads
Breast pads
Towel
Clothes to go home in
Plastic bags for dirty clothes
Vests/sleepsuits for baby x3
Nappies
Wipes/cotton wool
Muslins
Hat/blanket/cardigan for going home
I will transfer the dressing gown, slippers, kindle, hairbrush, phone, wash bag from the labour bag to the staying-in bag.
This all fits into 2 hand-luggage sized bags. The 'staying in' bag has wheels because I was given an excellent tip by someone on my antenatal thread that when you leave hospital your DH/DP will be carrying the baby/car seat, so you'll be left carrying the bag.