Simpletasks Dropbox Review

Just like todo.txt cli, this is 100% free (although donations are accepted).

For those who don't care about syncing there is a cloudless version while people who run Owncloud may opt for the Owncloud version.

This not only tells one's calendar (and thus any devices that sync with your calendar) about the todo, but allows all synced calendars to play an audible alarm when the todo is scheduled to be finished.

Let's one sort to-dos by due date then priority