The Tower of Terror is also a ride at Dreamworld.
Basically, you get into a cart type vehicle like a roller coaster. It is wider and shorter, though, 4 seats wide and 4 rows long, with roller coaster type should braces to hold you in. This cart sits on some tracks which go horizontal and straight for around 300m, then suddenly, within the space of about 50-100m, they bend and go straight up the side of the 40 storey tower (the same one used for The Giant Drop).
After getting strapped in, the staff check all the harnesses, and push the Big Red Button(tm). 2.2 megawatts of electricity powers electormagnets in the track which accelerate the cart from 0 to 160 km/h in 7 seconds. You then fly along the 300m of track rather quickly, and start heading vertically up the side of the 40 storey so-called Tower of Terror. Naturally, gravity slows the vehicle down, and it comes to a momentary standstill up the top, then falls back down.
This time you are in freefall backwards in the cart, heading back down towards the ground, along the horizontal track towards the start of the ride.
The whole thing takes around 20 seconds or something, and is quite fun. Personally, I prefer it to The Giant Drop on the same tower, because it is a little longer. But it still has all that adreniline rush, 40 storey freefall goodness.