I've been looking for such a plugin, but was unable to find it.
What's the idea?
By default WordPress allows posts to be published without any content or title.
With a plugin like this you could set a bare minimum of words which is required to publish the post. (for example 45 words, to get it even with the default excerpt lenght)
If it has not passed the minimum, the auther gets a warning.
Also, it's can be handy to set a maximum number of words.
When using WP more as a CMS with multiple authors, it can be handy to force a bare minimum of words. So authors have to write an introduction, instead of only posting images/gallery.
The maximum number of words, no clue why it's handy, but it probably makes an addon like this more complete.
What do you think about this idea?