If you already purchased all of the big stuff you need register for clothes, different sized diapers, wipes, feeding supplies, books, toys, dvds, there will always be SOMETHING that you need... what about bath supplies? Baby Motrin-orajel-gas releif - a thermometer?
Don't stress yourself out about it - just think of stuff you might need - if people buy things from it that's fine - if not that's fine too!