As millions of Americans flood theme parks this summer, two self-proclaimed roller coaster geeks are looking to crown the king of thrill rides.

"Coasters are getting higher and faster and the technology that keeps pushing is just amazing," said Clint Novak, who is a member of the Web site Coaster-Net.com.

He and Coaster-Net.com Webmaster Devin Olson ride the latest and greatest roller coasters and rate them on their site, providing readers with information about the rides' layouts, heights and speeds. Among Novak and Olson's favorites is the Rebel Yell (search) ride at Kings Dominion in Virginia, which "hits speeds of up to 56 miles per hour in around 3,400 feet of track."

But as thrill seekers continue to search for faster, curvier coasters, theme parks must also make sure their rides are safe.

"Before the sun even comes up we're inspecting the coasters making sure they're ready to go and ready before the first guest gets on," said Sarah Lovejoy, who works with Paramount's Kings Dominion (search) to assess the rides' safety.

Nonetheless, some incidents do happen. On Tuesday at Walt Disney World, a 16-year-old British girl suffered cardiac arrest after stepping off the The Twilight Zone Tower of Terror ride at the Disney-MGM Studios park. Authorities were trying to determine what effect, if any, the ride had on the girl.

So far this year, two people have died at Disney World. A four-year-old Pennsylvania boy died June 13 after riding Epcot Center's "Mission: Space." His death remains under investigation. But authorities concluded that the February death of a 77-year-old Minnesota woman who collapsed after riding the Magic Kingdom's "Pirates of the Caribbean" was likely caused by the woman's poor health.

Last month, the California Supreme Court ruled that amusement park rides in the state have to live up to safety standards of public transportation.

Novak and Olson believe that that ruling is over the top, and worry it might put a damper on new development.

"Millions of people wouldn't be rushing out to theme parks to ride these coasters if they were unsafe," Novak said.

Click in the video box above to watch a report by FOX News' Erik Liljegren.