The "ask a professional" feature is really cool. A couple of years ago some MIT students came out with a plugin for Word called Soylent [1]. It's the same basic idea, except it's backed by Mechanical Turk instead of a team of professional editors. Turkers suggest small changes and the changes are voted in or out of the final draft by other turkers. Pretty cool stuff.

[1] http://projects.csail.mit.edu/soylent/