XDeskCal is a pretty,fully customizable calendar features Todo-list,Appointments,Alarms,Holidays and displays its data on your desktop. It is a very lightweight application that doesn't use much system resources or take much space on your desktop.
Features :

Make a list of all the tasks you have To Do and remember.. Create lists of all your important events, anniversaries, things to do, etc. Define priorities and dates to do things, archive old reminders, print list, sort by date or task, and it uses whatever Date format the user's computer is configured for. Takes very little space on your desktop, and minimizes to the tray. Can also startup automatically, to help you remember.

Make a list of all the tasks you have To Do and remember.. Create lists of all your important events, anniversaries, things to do, etc. Define priorities and dates to do things, archive old reminders, print list, sort by date or task, and it uses whatever Date format the user's computer is configured for. Takes very little space on your desktop, and minimizes to the tray. Can also startup automatically, to help you remember.

A convenient tree-style to-do list. Fully customizable fonts, colors and categories. Easy and non-irritating to use. Minimizes to a tray icon, and pops up with a shortcut key. The tree has any number of sub levels. 9 customizable color-coded categories. Import, export, print, and copy to plain text. Save and load color schemes and settings.

Note/Todo/Reminder/LAN Messenger/Address book utility. This program was created to help in organization of daily work with
such features as ToDo/Reminders and sticky notes service along with address book and LAN messenger. The kernel of the program is easy-to-use tree-structured data holder. This program can be used instead of standard Windows messaging service or WinPopup and can be extended in functionality when used with our other products.

Manage any important dates, todo notes and contacts with an easy to use interface.

ToDo Organizer Deluxe is a flexible database management software with ready to use database solutions. Our software solution gives you an easy way to gather, organize and manage information about all your daily tasks, personal or business activities, or any to do items. ToDo Organizer is easy to use and very intuitive. You can use database solutions included in the software or you can customize them with Designer.

A Personal ToDo List is a simple but useful program for keeping a list of necessary Tasks to do at hand with an optionally set overdue list. Four different reports can be printed, it can be minimized to the systray, skins can be changed, and uninstall is included. Try it free for 21 days, $9 to register.

Get 'em Done is the todo list software for anyone who doesn't want to spend all day just learning how to use an organizer. Unlike other programs that force you to learn a "system" for organizing your life, Get 'em Done focuses on what matters: your task list. There is no fancy life-altering organizational philosophy behind Get 'em Done. If you want to spend your time completing your tasks instead of organizing them, Get 'em Done is for you.

Simple Project ToDo provides really easy project tracking based on to-do lists and simple priorities, allowing you to focus on your projects and increase your productivity. Simplify tracking of small projects, get organized quickly and focus on the big picture. Ideal for single developers and small teams.

Organise your tasks in a hierarchical tree so you know how much you have done, and how much you haven't! Quickly add and remove tasks, check them as finished, print out your lists, prioritise tasks and even add notes! ToDo even helpfully remembers the last .todo list you had open and reloads it for you on startup.