I run a travel web site. I am looking for a countdown clock that a customer can place a date, and time (ie 8am or 8pm) they are leaving on their vacation. The clock needs to show how many months, days, hours, seconds.

I get many requests for a clock that does this. Also if possible a way that they can copy the countdown to their computer.

Is this something that can be done? Does this script already exsist?