There are plenty. The question is what is the aim of this . Most of the programs make changes look unhuman.
I have tried some software but not very good result. I think it's because Google can check similar articles.
My experience has been that the software generated variations of articles read as if they were written by a team of monkeys at networked keyboards. There are loads of words there, including the important keywords, but they are of no use to a human who reads them. Thus, nobody is going to click on a signature link except perhaps to yell at you for wasting their time and bandwith.
Just search for articles rewriter in Google and you will get plenty of result. But don't rely 100% on the software. Take your time to edit it back manually or otherwise your visitor just click away in second. Remember, no software can beat the human brain itself.
I have heard good reviews for jet spinner, mostly because you have control over variations. But I am still not sure if it's such a good idea. You should probably get the articles re-written manually.
those of you decrying article rewriting software are well behind the curve. The technology has come on seriously in the last year. Here's a blog totally generated by machine, and every article is 'spun' automatically. http://mesothelioma.contentboss.com and here's a link to a full on article that has been spun once, by clicking a button. Feel free to use it, check it in copyscape, stick it it in an old sock, whatever. http://forums.digitalpoint.com/showthread.php?t=1144486 technology advances constantly. That's the thing about it. And why it's so useful.
my experience says getting a content rewriting software is foolishness as it mostly results with useless and senseless content that may be some how give advantage from SE but non of importance from the visitors, ur traffic will decrease, so instead of i that i will suggest u to hire a good content re-writer to do the work.
lets say you have 50 spun versions of your article, besides submitting them to directories lets say you wanted to post to your blogs. How can you easily update 50 of your blogs with the 50 different versions? What tools do you guys use?
shameless plug yet again - contentboss has an 'autoblogging' upgrade that does what you want. It also allows you to use 'free' blogs, like blogger.com, wordpress.com, i.e. no cost blogging.