The tops in homemade amusement park style entertainment is the Flying Fox.
In its simplest form a pulley is attached to a wire who's incline is slightly downhill so that the pulley rolls downwards on it's track. A person takes hold of the pulley and slides.
In its most complex and glorified incarnations it's still the same thing.
For your pleasure here's some ASCII art to describe the contraption. (Please note that in normal circumstances the wire would not be threaded through the participant's eye sockets.)
o--------------------------- this is a wire
/|\ that would normally
\\ be going downhill
====
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-------o------------------------
/|\
//
====
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--------------------o-------------(==|
whee! /|\ |
// |
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== ======
| |
-------------------------------o--(==|
/|\ |
// |
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----------------------------------(==|
"I made it! -- o |
I'm king of /|\ |
the world!" / \ |
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nb. Some might suggest that the numerous laws of physics just trampled in my ASCII diagram render the diagram useless; but they would of course be wrong.