iCal

iCal is Apple’s built in calendaring application. You either love its simplicity or hate its limitations…

  defaults write com.apple.iCal 'Default duration in minutes for new event' 30 

  defaults write com.apple.iCal IncludeDebugMenu 1

This allows you to, among other things, change the number of days displayed in the week view.

• Using the mouse scroll wheel with Alt/Option held down changes the visible time scale.

The following cover not only iCal itself but other calendaring applications - since most people visiting this page are looking for ways to migrate or integrate with them:

• BusySync
• RemoteCalendars, an Outlook plugin for subscribing to published calendars.
• Outlook2VCal - exports Outlook data to a single vCalendar file
• iAppoint - exports Outlook data to .ics.
• Mozilla Sunbird
• Fun With Calendars
• iWebCal (a PHP viewer for .ics files)
• PHPiCalendar
• iCalibrate (CAM for iCal)
• iCal calling iTunes
• RSSiCal (RSS import)
• http://jical.sourceforge.net/
• Enabling Outlook Users to view iCal Invitations