My Daily Planner - Organize your day with pen & paper. Free printable template.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
Amazing Marvin - Customizable personal productivity tool
Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.
Plan - Plan is a better way to organize.
Strikethru - Strikethru is a kind of to-do list notebook for managing work lists and staying updated with the important tasks.