Super easy art center, since they're getting nearly old enough to trust with having it out. Can also do it easily by just hanging a whiteboard from target and adding the clips to hold paper, and a little bucket to hold supplies.
Project Idea: DIY Paper Roll Wall Easel — Infarrantly Creative
Saw this here http://www.apartmenttherapy.com/how-to-make-a-wall-easel-infarrantly-creative-183699, but it was made by Becky elsewhere (link in article, I believe). As she says: "What small kid doesn't like to draw on the wall?"