What if no-one uses that website anymore, what is the world price going to be? Where else can we get a real graph of what's going on?
Its an exchange so the buyers and sellers dictate the price.
If no one used the site anymore, the price would depend on whether there was a proportionally larger decrease in buyers or sellers.
sellers > buyers the price goes down
buyers > sellers the price goes up
That's basic supply and demand.
Look at here:
http://bitcoincharts.com/markets/
http://bitcoincharts.com/charts/volumepie/
As you can see, the last 24h on btc-China was more trading than on the 3 largest BTC-USD platforms (mtgox, bitstam, btc-e). On other days mtGox as the lead.