I would go with a lot of the above ...
cleaning vouchers
massage/manicure/pedicure something to treat yourself that you wouldn't normally do, but would enjoy
a nappy serevice, you don't need to clean them that way
books, they can never be too young or have too many books
vouchers for you to spend at a time that it suits you.

Perhaps give them a list of the things that you don't need ~ it can cover things that you already have, and things that you don't want