Good: Waterproof quilted fitted mattress pad
I registered for and received 2 Carter's Keep Me Dry quilted fitted mattress pads. They're pretty much tiny versions of the mattress pad you'd use on your own bed.
We used the crib mattress pads for the first few weeks, and then realized that it was a huge pain to change both the mattress pad and the crib sheet whenever C spit up or had a blowout in the crib. Since our crib mattress has a plastic outside, it's waterproof in and of itself...so the waterproof mattress pad is not necessary like it is with normal adult mattresses. Cribs are supposed to be rock-hard anyway for SIDS purposes, so it's not like this was providing much padding. We stopped using the mattress pads about 2 weeks in and haven't looked back. I wish someone had told us how unnecessary these are!!