(All 23.11.2010, copyright Steve Sainsbury/Rail Thing)
This is the monorail that serves Disney in Orlando, Florida. I didn't really know anything about this system before visiting, and was quite surprised that it was far from being an amusement park ride as expected. It actually serves a vital function, linking the Magic Kingdom, Epcot and some other Disney attractions to each other and to the Transportation Center. Trains run every couple of minutes and were packed. I was very impressed by the PA system on board which told us exactly why we were waiting for a few minutes just before our station (one of the trains was being switched to the Epcot route). All in all quite an experience.
Monorails can work in very dedicated situations like this - there's a similar short system at Orlando International Airport for example, but must cost a good deal more than conventional rail. A high capacity tramway would probably do the same job at a half the price - but you would lose the experience of seeing everything from an elevated position.