Example Goal: Learn a new language
Beeminder is a great tool for learning a new language! Consistent practice and study are one of the biggest keys to picking up a new language, and what better way to ensure those than with money on the line? Another reason it's a great goal: multiple integrations with great language-learning services to report your progress automatically. That way you can worry more about the vocabulary and less about remembering to update your data all the time.
But if you don't use any of those apps, you can still create your own goal for whatever metric and method of data entry you'd like, of course!