First in New Zealand, later on some high ropes courses, I’ve been terrified by the adult versions of the old children’s swing.
Here’s a run-down of the three biggest:
Essentially, you strap into a chest harness and step off a gorge. Initially, you plummet straight down for 160 feet, but then the ropes catch a line that spans the gorge. Immediately, the rope becomes taught and catches you, allowing you to you swing back and forth, like a pendulum. Nothing in my experience has ever shifted from terror to joy so quickly. I had always thought the Zambezi Gorge Swing was the world’s highest swing, but it’s not. I think it’s the third highest.
World’s Highest Swings – Gadling

Zambezi Gorge Swing – photos
I thought you meant really Giant Swings…like on High Bar!