After several days’ brain storming, I have a rough idea of the To-Do Application.
Since, this is a very simple application. I'll use a client-base model to develop this application. And, the platforms independency is one of my expected requirements. I'll use Java (http://java.sun.com) as the development language.
I believe a client-based application need to have a very attractive user interface and look & feel. And, only have this make people want to use it. So, I'll try to use the SwingLabs library (http://swinglabs.org/index.jsp).
I think the coming two months will be spend on testing the usage of this library