My in-laws just got their new home done. Can anybody suggest any house warming gifts?

If they are religious you can gift them Swarovski studded idol of God or a Goddess. Else you can gift some hand made painting, if you are good at at or gift say, 30 or 40 pots with different varieties of flowers or plants in them. If they like reading, gift them books by their favourite authors. You can also present a nice collage of pictures of them and all of you kids and grandkids along with them in each pic. Material things they anyway can buy and must have bought to fill the home, but I think a personalised gesture would real mean a lot. I suggest, even if the gift is small or big but should have your personal involvement in it.