http://www.gogaminggiant.com/2010/12/03/naild-review/
When you're not soaring with the birds, you're tearing through forests, buildings, and wrecked planes at breakneck speed while constantly trying to get the best of your opponents. At all times, you drive at ridiculous speeds, which is greatly encouraged by the number of different ways you can build up your boost gauge. The most obvious method is by driving through flaming poles and hoops, but boost power is also earned by crashing opponents, landing on them, driving/flying through small spaces, nailing perfect landings, and other more complicated methods. Sometimes, it also seems like the game gives you a little boost here and there just because it wants to. http://naildbiter.com/EZaeZ