If you prefer to keep your GTD application on the desktop instead of using a web app like Remember the Milk, WinWorkBar is worth giving a try.

It's less than a 600kb download and packs a ton of functionality into a tidy sidebar. Features include a time and date display, calendar, task list, and notepad.

Tasks can be created as a one time occurrence or repeating event and can span multiple days. You can also specify percentage complete, not just whether or not a task is finished. The task view can be filtered a number of different ways, including progress, category, priority, or date (creation, change, etc.).

Notes can also be assigned to a range of dates - helpful if you've got an important event coming up and want to be reminded repeatedly as it approaches.

Hotkeys are supported for task and note creation and to show or hide the sidebar.

By default the sidebar autohides, though it's perfectly suited to full-time display on a widescreen monitor. A quick click on the menu button can turn off hiding. WinWorkBar also places an icon in the system tray at startup which provides right-click access to creating new notes and tasks.

WinWorkBar is a free application for Windows only.