There are a wide range of applications that might benefit from the content rewriting capabilities of ArticleRewriterTool. The obvious applications include building content for your website or blog. Other applications include any kind of essay or creative writing (virtual or not), twitter, newsfeeds, Craigslist posts or even paid article writing services.
I've ranked websites in the past with spun content, and now they are still on #1 position of google. First year (2014) google found me because my spun was really bad, many paragraphs were just copied and my position drop from #2 to around #20 after a panda update. Later I cleaned all my text with better spun (I didn't buy any article!), my ranking went up again, and with more backlinks I reached #1 and it is still there