Aha - Aha! is the new way to create visual product roadmaps. Web-based product management tools and roadmapping software for agile product managers.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
productboard - Beautiful and powerful product management.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
ProductPlan - Cloud-based product roadmap software solution
EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.