stickK - stickK enables users to form commitment contracts to help them achieve their personal goals.
Habitica - Habitica is a free habit building and productivity application.
Becomr - Reach your goals, build healthy habits, & improve your life
HabitBull - HabitBull
Beeminder - Beeminder
Coach.me - Coach.me is a coach that goes everywhere with you, helping you achieve any goal, change any habit, or build any expertise.