What are some alternatives?
When comparing Task Coach and Amazing Marvin, you can also consider the following products
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.
Google Tasks - to-do list app that integrates with Gmail and Google Calendar
My Daily Planner - Organize your day with pen & paper. Free printable template.
Toodledo - Toodledo provides a set of tools to increase the productivity.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.