Textpattern Resources at textpattern.org

Count down to any arbitrary date/time; by default the current article’s Posted date.

Features:

• Counts down to article posted, expired, modified time; to any time given in any article field; or to any arbitrary time given as an English date
• Supports <txp:else /> conditional so you can take different action when the specified time has been reached
• Display number of years, months, weeks, days, hours, minutes, seconds as either an absolute number (‘10 days to go’) or a date-based number (‘1 week 3 days to go’)
• Counts up if the event has passed

Simply chuck the <txp:smd_countdown> tag in an article Form — the first part of the container will be executed when the given time is reached; the <txp:else /> portion is executed otherwise. Use the multi-purpose <txp:smd_time_info /> tag to display whichever bits of time you wish inside the container.

NOTE: it is not a real-time counter/timer. But there is nothing to stop you seeding a javascript- or flash-based timer with the output of this plugin.