Via Casual Keystrokes, I found this cool site for all you future engineers where you can experiment with roller coaster building online.

It is your mission to design the coaster so that you can achieve maximum thrills and chills without crashing or flying off the track (unless that’s how you like your coaster to work!).

You accomplish the “mission” by changing the speed, height, gravity, friction, etc. I had lots of fun playing with it!