When I had my first son my one daughter was 15 mo old and when I had my 2nd son my 1st son was 2 yrs and 1 week old. I had 2 in cribs at a time... so I did need another crib, but I was given one as a hand me down. I also loved my double stroller (but see you already have one). The other things I needed was a new highchair cause my others still used them (we had 3 highchairs at the table for a while), a new car seat (even if you have a newborn one - you will need a bigger one soon, but you can wait & ask for it for Christmas if you want to.)
Mainly with the younger ones I just asked for the everyday stuff - diapers (all sizes - not just newborn or 1's), bath supplies, diaper cream/vasiline, laundry soap, diaper wipes, new nipples (eventhough I nurse) & nukes (some babies use them some don't), a few new sheets & blankets (more so if your 2 yr old is still in a crib or a toddler bed) and a few outfits cause even on my 5th I want something that is just this babies. Something else - I know it's not very personnal, but gift cards for the grocery store, Wal-mart & Target so you can get anything you find you need after the baby gets here or for local resurants that have carry-out so you don't have to cook as much when you first come home.
Also, I have seen where moms are having "sprinkles" instead of "showers" for 2nd, 3rd or 4th kids - I guess a "sprinkles" is a party where they bring homemade frozen meals that you can just pull out of the freezer, heat & eat it. Which would be a huge help when you come home from the hospital & have to tend to a newborn & a 2 yr old.
Congratz on the new baby & the 2 yr old. I hope things get easier for you!! I'm sure your are getting tired of being in bed & looking forward to a party w/ friends & family!! I hope everyone you love will be able to make it & you have a really good time!