Interesting topic. I'm actually writing an article re-writer/spinner right now.
What makes a article re-writer usable?
I've found that everyone seems to have a different opinion. So far I haven't found one that does what I want and that is "everything".
I only want to type when I have to or want to, I want synonym find/replace/group, I want sentence spinning without having to highlight, I want phrase editing with suggestions, and I want the software to learn as I use it (this is a big one) and provide future suggestions, and finally I want it to submit to the major article directories automatically with tracking.
If you have specific ideas on what you want in a software application, I can try to accommodate them. I do plan to sell this software (WSO, of course) when it is complete.
It is definitely a difficult task because there are a lot of different things that take place when manually editing an article that are hard to put gui's to.
powerarticlerewriter has a nice clean interface but still requires a lot of effort and has limited features.