There is, it is claimed, an early version of the Serenity script up for grabs on eBay; it’s an earlier “kitchen sink” version, where Joss was unimpeded by thinks like, oh, budget and time and the laws of physics.
The referenced post gives a summary of the changes from the filmed version. By and large, the filmed version is darker and tighter and arguably better — but given that one of the joys of the show (and Joss’ writing) is his dialog, there’s all sorts of nice throw-away goodness that got, well, thrown away. And (sad glee) Book is still part of the crew in this draft.
As the poster puts it:
This would have made a really good Firefly movie. It wouldn’t have been Serenity.
Here’s hoping that it gets published “for free” someday.
(via Whedonesque)