I would find it strange to hear about a registry for a house warming. In Australia, in my circle of friends, we rarely give gifts for this kind of thing except a token plant or bottle of wine.
When I moved into my first (owned) home, my dad and sister gave me a plant and some wine glasses and I was grateful because I didn't really expect anything. Nothing from friends.
Having said that, when I first moved out of home into my first rented flat, a couple of close family friends bought me a washing basket and filled it with cleaning products. Their rationale was that those products can be very expensive, especially to buy all at once. This way, I had everything I needed and they all get used at different rates so I didn't have to buy all at once again. This was absolutely the best house warming gift ever! It was basically washing powder, stain remover, ironing spray, cloths, sponges, scourers, dishwashing liquid, toilet cleaner, bathroom cleaner, general spray n wipe cleaner, pegs. So if you're ever looking for ideas for a house warming or moving out of home gift for someone, i strongly recommend this!