PlainSight Desktop Calendar is a great looking desktop calendar which can be fully integrated with Windows wallpaper. It stays on your desktop and shows the days of the current month. It can display Microsoft Outlook data, which you can directly manipulate, and weather forecasts from weather information servers. It also uses high-quality fonts, looks pretty, and has lots of skins.

Desktop iCalendar is a customizable desktop calendar program that gets calendar, events, to-do list and weather on your desktop. It allows you to sync local calendar file with Google Calendar. So you can edit your Google calendar offline, and share the calendar data on multiple computers. Calendar information can be entered from any computer and the data will become visible at all the computers.