Need for houses, pretty much. There's been weeks when they didn't have anything that I would use in my houses (like the crafting signs) where I was a little relieved that I could save money that week. xD
Both for my houses and to sell on the trader 3-6 months later for more than I bought them for. I've turned a pretty good profit off flipping the items.
The purpose of art is washing the dust of daily life off our souls. ~Pablo Picasso