#18 FollowUpThen
Used For: Productivity
Price: Free; $24/year for the premium version
FollowUpThen is a productivity service that lets users to create and schedule email reminders, associated with specified activities. Premium users can also receive SMS alerts and other offerings such as calendar integration and reminder customization.

#17 HabitForge
Used For: Personal improvement
Price: Free; $10/year for the premium version
HabitForge let users to change and develop new habits by setting up emails, notes and by sending customers with notifications on whether the task is done or not. This free web app emails you daily asking you a yes or no question about whether you followed through on a habit you want to establish.

A successful completion of a particular task for 21 days in a row can get you a congratulations email. Habits can be developed alone or with groups. Users of the free, ad-supported service can set only one active public habit at a time.

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