Freefalling on a NASA astronaut trainer plane. ZeroG is a physics lesson about the difference between weight, mass, and momentum. Zero weight, but it still hurts when bumping around. Not to much though. Point being that a 170 pound person may weigh zero pounds in zero gravity, but they still hit...

Very cool video of astronauts popping A waterballoon in space.

A clip from the series The Elegant Universe regarding some aspects of General Relativity and gravity.