The Blue Flash

This is pretty old, but pretty awesome nonetheless. And it must be seen to be believed.

Some dude in rural Indiana a) liked roller coasters, b) had a lot of time on his hands, and c) was knowledgeable about steel manipulation, so he built a roller coaster in his backyard. It's called the Blue Flash and it goes upside down and everything.

You can see a video of it here, and WNYC's The Next Big Thing (kinda like an NYC version of This American Life), did a segment from here.

Enjoy the ingenuity!