I really like Celtx. It is a pre-production program that allows for everything from keeping track of storyboards and call times, to letting you write and format your script. It even includes an option for organizing your script via note cards.
Oh, and it's free.
In other words: If you've been thinking about purchasing Final Draft, download Celtx for free first.
And now that Celtx 2.0 is out, things look to be even better than ever.
So, go ahead: Check it out.
Your Media Production Mentor