Quit Now! Is a free application that enables you to keep close track of your habits as a smoker, so that you can then view statistics, updated in real time, regarding your progress in quitting. You'll see how much time you've gone without smoking, how many cigarettes you haven't smoked, and how much money you've saved by not buying tobacco - three good reasons to fight the urge day after day.
This tool also includes a list of achievements that you can unlock as you go more and more days without smoking, making quitting into a game in which reaching your goal is 'expert level'.
Thanks to iCloud, once you've created an account with Quit Now!, you can use it from any device without having to reenter your information. That means you can keep track of your progress no matter where you are.