Nesting tables are an old trick for small spaces and they work great in a kid's space too. These tables also have hinged lids for storage inside making them extra useful.
We really like the colors and simple Shaker design of these tables, but you could also just buy a few tables in different sizes and create your own nesting tables. Kids can pull them out and use them as stools when friends are over, for an impromptu tea party, or as a step stool.
The above tables are available for pre order at Areaware.