I’ve tried many note-taking-task schedular applications. However, I always felt they’re either too bulky for such a small job, or too complex for such simple actions. The best of all that I’ve ever tested, the best is ToDo. As the name implies, ToDo is a simple to-do list application that keeps you on track.
Each to do item can be linked with a file on your computer, a URL, such as the address of a website, or a contact from your address book. The linked item can be opened directly from the ToDo window. ToDo items can also include notes, priorities and deadlines, which can be set as reminders in iCal.
ToDo is applescriptable, includes plugins for Address book to quickly set contact reminders and a plugin for Quicksilver to allow rapid creation of ToDo items from the Quicksilver interface. ToDo can import iCal to do lists, and export lists from to do to import into iCal. You can set your ToDo deadlines as events in iCal with a single click. You can sync your ToDo lists on multiple computers using .Mac.