http://www.alllooksame.com/
Try to guess if these people are Chinese, Japanese, or Korean. It's harder than most people think.
You have to register, but you don't have to use real info.
It's determining whether they are Chinese or not that's hard, because China is huge and continental, there exists people in China who looks like every Korean and Japanese. Population size and genetic diversity predetermines this.
Currently your best bet is by fashion and behavior, but as China becomes wealthier, it will be harder to tell.