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Elaborate a bit more.

Tagging is the assumption I'd take from your post, but your too vague.
 
Even better than Final Draft is Adobe Story. It's a FREE online service that lets you tag (essentially creating metadata) your script for easier post-production (great for posting movies and clips online), has great collaboration tools, and has that same Final Draft script writing features but without the annoying bugs. Check it out here: http://story.adobe.com.
 
I actually love [url="http://www.celtx.com]Celtx[/url]. It is free, open source, cross platform, and has a lot of great features beyond script writing.

The script writing feature is pretty fantastic IMO, and they have a great forum, support, tutorials, advice, articles, etc.

Best on your venture.
 
By far my favorite is Scripts Pro on iphone/ipad. Its intuitive and gets the job done.
 
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