Closet studio storage-- this is similar to what I want to do with my office/craft room. Remove the closet doors that slide and put all the supplies and things in there with some nice storage/organization setup.
Take a 2 liter soda bottle, poke holes in it. Attach to a garden hose. Toss over a tree branch and let hang for a kids water sprinkler. You can loop it over a tree branch and let kids bat it around for more watery fun!