If you are looking for the locations of amusement parks and roller coasters, the best collection for Google Earth I’ve found so far is from BozAdventures.com. They have posted their database of amusement park placemarks as a network link at the Google Earth Community. There’s a bit too much blatant commercialism in this, but it still is fun to look at all the parks and to find out how well you can see the rollercoasters in Google Earth.
Once you download their network link from above you will see the BozAdventures logo icons. Currently, their focus is clearly on the US, but there are a few parks in other countries. Zoom in further and you will see there is a lot of information contained here (literally hundreds of roller coasters are marked). When you click on the placemark you will see their logo blazened in the description and a sometimes useful link which will take you to their database entry for the placemark. Not all of the entries have information, but you can sign up and add your own feedback to their database. I think they should allow anyone to update the data (more like a Wiki), and then their data might get populated more quickly. Anyway, this is a fun collection of placemarks!