Windows/Mac/Linux: TextFlow is an Adobe AIR-based word processor with a new and innovative take on document collaboration. Rather than offer real-time updates when multiple users are working on a document like Google Docs, Zoho Writer, or previously mentioned Gobby, TextFlow imports multiple Microsoft Word documents, analyzes all of the differences, and provides robust tools for merging, accepting, or rejecting any of the changes therein by a master editor. Say, for example, you send a document to several co-workers. Even if you track the changes, you'd still need to manually merge all the suggestions and changes into one document once they got back to you. On the other hand, you could drag and drop all of the documents into TextFlow and let it analyze the differences, making it significantly easier to create a single document using the best changes available and without making mistakes. When you're done, just export the final result back to a Microsoft Word doc. If you're still not entirely convinced, check out TextFlow's intro video for a better idea of how it works.
TextFlow [via CNET]