A few months ago, a friend of mine introduced me to slacklining-a form of tightrope walking that's making its way out from campsites and climbing spots into parks and playgrounds all over the country.
With the combination of the fear of falling and the exhiliration of taking your first few steps, slacklining has a way of turning a day at the park into an adventure. The only complaint I've had is that slacklines usually takes a plethora of webbing and a sailor's knowledge of knots to set up.
Gibbon Slacklines has amended this problem with their series of slackline kits-they reduce the complicated tangle of webbing to two lines that are connected and tightened with a compact ratchet. With these kits, you'll probably spend more time talking yourself onto one than you will setting one up.