I was going through Jono's screencaps on Twitter / Twitpic and, remembering the artwork in my old 50k house in Salatu, was reminded of something I'd like to see: customizable artwork.
http://twitpic.com/6jm32p/full Top floor, next to the door
User uploaded would be nice, but I'd even be happy with being able to choose from a gallery.
Low priority, to be sure, but just a thought. :)