It was August; my budget was $0; I had to entertain several dozen kids. We went tobogganing. Go to a couple of cardboard recycling bins, or visit a couple of furniture stores, etc, and obtain a bunch of cardboard boxes–the bigger the better. Cut them (on one side, of course) and tack them to the hillside in a shingle pattern (so that the top of one is UNDER the bottom of the piece above it, of course) using tent pegs (or whatever else you figure out.) The kids will use smaller pieces of cardboard to slide down the hill. (Make it strong before you start and it will last–we made one that endured 4 hours of abuse.) The speed they’ll reach is actually pretty decent. A couple of games we played with this set up were: Bowling (people in boxes at the bottom of the slide are the pins), Spin the Sledder (by grabbing only one  corner as they zip by), Surfing and other assorted stunts (try duct taping a small piece to each foot and ski down!), Races, and Pile-Ons (using a large box we sent 25 kids down in one slide.) Like I said the speed is pretty quick, but not fast like tubing on a wet-icy slope. No one got hurt the four times we did it.