Miriam de Paula

WP Coming Soon is a plugin that adds a countdown clock in the Coming Soon page. This plugin uses Keith Wood jQuery plugin. See it at: http://keith-wood.name/countdown.html.
[BASIC USAGE]
Put this <code>if ( function_exists('get_countdown')) get_countdown();</code> where you want to display the countdown clock…
If you want to use the countdown timer within a page or page template, you can use the shortcode <code>[wp_coming_soon]</code>

WP Coming Soon

WP Coming Soon is a simple plugin that adds a countdown clock in your Coming Soon page... Nothing more!

twinpictures

T(-) Countdown is a customisable countdown timer that can display years (optional), months (optional), weeks (optional), days, hours and seconds. This plugin is the next generation of T(-) Countdown Widget. Note: a dedicated sidebar widget is not included as shortcodes can now be used in most sidebars.

T(-) Countdown

Display and configure multiple countdown timers in years, months, weeks, days, hours and seconds in a number of different styles.

WP Coming Soon vs T(-) Countdown