This roller coaster was made originally by Genekid. What I did is fix the roller coaster so that it uses the modern 1.6-style Booster Rails instead of the adjacent-minecart glitch, as this no longer works as of Minecraft Beta 1.6. I also removed a column of lava inside one of the downward spirals because Minecarts now despawn when they touch lava. I do not take any credit for this roller coaster, I only fixed it for 1.6+.

Original coaster: http://www.planetminecraft.com/project/the-10110101-rollercoaster/