I have started to put the city to a use and put a sample setup there that should give you a good overview what you can do with minecarts. It shows only the most basic stuff. You will have to refer to the manual for detailed instructions. In order to find the setup, please go to the city through the blue gate in spawn and go up one stair in the same building. You can try out all the stuff directly there.
Regarding the city as a whole I am planning to sooner or later (rather later) to build more and more instructional setups in the city. I would be happy if someone made a electric services building that houses the most common redstone setups. There could also be a agricultrual ministry that shows the different plants, trees etc.
I also updated the Minecarts Page on this website.