Well I just went through this a little while ago.
I must have downloaded and torn apart a dozen scripts.
Didn't really find anything that really fit my needs, so I built one myself.
A pretty good/free script IS available, however, here: http://sourceforge.net/projects/ltwcalendar
I do suggest you at least go through a basic tutorial to learn how to put one together, in the event you download a script and have to tear it apart to get it to do what you want.
This is an OK tutorial for starters: http://www.phpfreaks.com/tutorials/83/0.php
Hope that helps.....
