One of the best things to do in Google Earth is find weird stuff:
Photo at the Register
Google Earth forum: Huangyangtan Mystery Landscape
That's the place in the middle of the desert where the Chinese Army has constructed a scale-model replica of the entire region of Aksai Chin (occupied by China since the 1962 war with India). At 1:500, it's still 700 by 900 meters big ( = several football fields). Next to it is a base with dozens of troop transporters seen coming and going. The duplicate shows everything: rivers, lakes, roads and snow-capped mountains. It's basically a landscape within a landscape.
The problem is that nobody has been able to figure out the function of this thing. The world's biggest miniature golf course, perhaps? China's own Area 51? That's why it's the subject of so much discussion in the blogosphere.