Rainlendar is a customizable calendar that resides on your desktop and shows the days of the current month. It's possible to add events and tasks to the calendar and the appearance can be customized with different skins. Rainlendar can also show the events and tasks from Microsoft Outlook and Mozilla Sunbird. The events can be synchronized with a server, which will allow you to use it e.g. at home and at work. There are plenty of other features too.

Features:
Small and lightweight
Different type events can have different appearence
Supports Windows transparency
Synchronizes events between several clients
Localized for multiple languages
Shows an alarm when an event is due
Supports iCal files.
Shows Outlook's appointments
Includes a todo-list
Works also as Litestep plugin
Displays the current date in tray icon
Can stick to the desktop (i.e. doesn't hide with Show Desktop)
Hotkeys for quick access
Easy skinning with an UI
Can be controlled from 3rd party applications with !bangs
and more...

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