I'm working on my book right now, and have to write some text as well :-). My most frequent error is typing some initial characters and trying to autocomplete them with ctrl+space. ...and word silently ignores that. Such a plugin would be a killer feature for every netbeans, and even eclipse developer. It should be doable. Word has to maintain internal database for spellchecking anyway. This could be a killer feature of e.g. OpenOffice :-).
NEW: Online Workhop Effective WebApps without Frameworks is also coming to: MUC Airport.