Under bed boxes are nice for some toys and other clutter. Also baskets on the shelves looks much neater than having things setting out. I love the way baskets look.
A really inexpensive thing is to buy banker's boxes and contact paper for the kids to decorate for some of their items - but it doesn't look "high end" LOL but it works.
I like to use inexpensive 3 ring notebook for kids art, papers etc. They come home from school, you can check out the papers, 3 hole punch them and stick in the notebook and then glean things out every few weeks. If the artwork is oversized you can scan it and put a facsimile in the notebook, fold the artwork in quarters and tuck in a manilla envelope that you have 3 hole punched and put in the notebook.