Chalk Board Paint- I love the idea of this but dont know how well my asthma ridden children would respond to the dust. But, one day in my future very ventilated house, we will use it! You could use it on walls, dressers, table tops, large pieces of wood, etc..
Canvas- Childrens artwork could be modpodged onto canvas. Another good idea is button art ! whatever it is, canvas are always very nice!
Bedroom hideaways! Some extreme, but amazing. I wish I had one....(for the kids of course...)
Storage- most important
Thats all for now, but will update or have part two in the future!