The best play space of all may be an empty expanse. Give your kids a roll or two of painter's tape and let their sense of make- believe take over, à la Harold and the Purple Crayon. Roads and farms, four-square courts and hopscotch boards: anything is possible. The low-stick tape can be used on most carpeting and flooring (and furniture too!), comes in several different colors (we've found blue, green, and yellow), and can be removed without a trace when playtime is over.