GE's idea using lime jello over a cold winter night on the second or third floor. Expensive, and you need some help you can trust, but highly effective. I got really pissed off when they nixed that one this year for hotwiring the buses and parking them across the driveways as barricades.
Get a black wire (or paint it black), coat it along its entire length with oil or some other grease, and string it at a diagonal along any wooded part of the nearby roads. To avoid serious charges, make sure the, uh, "landing area" is reasonably clear and flat.
All of my other plans from the past hinge strongly on not getting caught, and generally involve a jail term and/or lynching if you do, so I doubt they're your sort.