Ricky Carmichael's Motocross Matchup Pro (iPhone iPod)
CheatingDome.com
Bonuses
Always remember to collect the glowing tool boxes whenever you see them as these will give you bonuses.
Landing
It is crucial that you make sure that your bike is angled in accordance with the racing surface when landing otherwise you will not be able to keep your speed up.
Stunts
Unless you want to crash spectacularly make sure you have enough height to finish your stunts when you swipe on the screen to perform them.