Leading Zero : On/Off
Show/Hide each item(day,hour,min,sec)
Show/hide html elements on the host page by id(#) and class(.)
Execute javascript function on Target Time
Free format
<hour00> <min00> <second00>


two lines style
==========================
000  00  : 00 : 00
day hour  min   sec
==========================

take an action on those who are on the page when the countdown was zero
take an action on those who come to the page after the countdown was zero

Statistics
How many people got redirected?

Redirect after 100 seconds when the user come to the page

Messages 
3 days=>3 more days
1 day=>Today is the last day!
1 hour=>It will end in 00:00:00