Rhett does the “shoot the falling target (aka monkey)” demo, and solves the kinematics. This was the demo that got me truly hooked on the idea that I wanted to do physics, after my neighbor set this demo up in his basement, albeit with a blowgun and with a cruder triggering mechanism.
Mythbusters, bullet dropped vs. fired. Give the boys credit for honesty! The few milliseconds divergence measured is required by the elliptic not conveniently-approximated parabolic orbits of the two projectiles (and other stuff, llike traversed air and geoid curvature).
http://dsc.discovery.com/videos/mythbusters-dropped-vs-fired-bullet.html
http://scienceblogs.com/dotphysics/2009/10/mythbusters-bringing-on-the-physics-bullet-drop.php