SEO measure keywords in posts as they are being written

HI

Love your work and aren't you all nice, the dark blue is good on the eyes after many an hour clicking around your site.

I was wondering if there is a plugin that will measure the keyword quality of a post as it is being written and will not allow a post if the quality of the keywords isn't there. It would we be extra great if it would have features like copyscape to stop people just pasting content into the posts after all we don't like plagiarism. If it is about could I get a link please.

Thanks in advance.

Dave