All five of these tools are available in PCWorld's .
Some habits are things you want to do every day, or nearly every day: Exercise, for example, or writing. Jerry Seinfeld is said to have used "productivity chains" in which he would do something each and every day, and never "break the chain," and in this way make steady progress. is a slick free service built on this concept, which lets you track any number of habits. For every day when you've done what the habit calls for, simply log into Chains.cc and mark the day as done. Whenever your chain grows by another week, Chains.cc will offer you an easy way to brag about it on Facebook if you want to. The top of each chain shows your longest streak, as well as the length of your latest streak.
Chains.cc is shiny, but it is very simple. , another free service, has been around for years and looks a bit dated by now, but it offers more options. You can use Joe's Goals to track habits that don't require daily repetition (for example, if you have an exercise routine you do every other day). Joe's Goals can also track bad habits: For example, if you're trying to quit smoking, you can use Joe's Goals to log every day in which you've smoked. Each day gets a numeric grade composed of the number of good habits minus the number of bad habits you've logged for that day.
Not all habits call for daily repetition; some habits benefit from flexibility: Your plants will probably not die if you fail to water them exactly every three days. Then again, if you forget about it for two weeks, that might become a problem. is a unique application for dealing with just this sort of repetition: Each repetitive task gets a range of days in which it is okay to do, and Sciral helps you keep track of these tasks and do them in a timely fashion (not too often, but not too rarely).
If you're looking for more powerful motivation and accountability, you may want to look into . This unique service lets you set a long-term goal with weekly check-ins. As you set the goal, you can commit a sum of money to making it. On every week when you've made the weekly goal (or kept up your habit), you get to keep your money. But if you fail to make the weekly goal or practice your habit, some of your money goes to charity. If that isn't a strong enough motivator, SticK can also donate your money to an "anti-charity" of your choice--an organization to which you really don't want to send any of your money. StickK also lets you pick referees who know you and can keep you straight.
Finally, there's , a service that offers a comprehensive approach for evaluating your life and making steady progress toward your long-term goals. Lifetick starts you off by naming your core values in life. You then link goals to each core value, and make a plan for each goal. Plans can include repetitive targets--in other words, goals. Lifetick's interface takes some getting used to, and its plans don't support nesting tasks, but its approach is both friendly and thorough.
Whatever tool you choose, creating new habits and achieving your goals still takes determination and persistence. But with the right tools and support, it can be easier than you think.