frank gruber compares some todo-list tools:

“Time is our most valuable commodity. Productivity pays. Procrastination costs us time and money, and leaves us stressed, exhausted and unreliable in the eyes of others.

For many, the classic “To Do” list is the remedy. But for heavy web users, there are a number of recently launched to-do list products to choose from, with convenient sharing and other features, and easy to use interfaces.”

have a look:
- Getting Things Done tools