Friends of ours recently moved into a new home. As a housewarming gift I followed the age-old Jewish custom of bringing bread and salt as the first items into the house.
I put them in a pretty tea towel along with a bottle of Extra Virgin Olive oil and nestled everything in a matching bowl.
It is also recommended to bring some Jewish books and a charity box into the home even before the movers bring the rest of the boxes. This establishes the Jewish flavor of the home--which will hopefully be a haven of study and kindness.