I haven't rode it personally, but I have heard that the "Big Shot" ride in Las Vegas is about as "thrill" as a ride can get. The ride is one of those that shoots you up along a tower at high speed and then you stop very fast at the top. The catch to this ride is that it is on top of the Stratosphere hotel.

The Big Shot is the highest thrill ride in the world.

Also the two "dragon" roller coasters at Universal's Island of Adventure are call the Dueling Dragons one is Fire and the other is Ice. If you get the chance to ride them, riding on the front row is definitely worth it for those two.