I use no tools whatsoever. I just shove aside any distractions aside and concentrate on writing. As for increasing word count, well, I can't really give any useful advice, because my word count increased over time simply because I got more acclimated to running my mouth(?) longer and longer in my reviews. My early reviews used to be ~800 words, but now I can't do less than ~1300 to save my life; I got too much stuff to say and/or complain about now to ever be so concise again! In fact, I just looked at the review I wrote yesterday--1499 words. Sounds about right. And I know for a fact I've got at least 4 reviews over 1800 words.
So really, the secret to productivity is to not get distracted, and the secret to longer word count is just to write about something you're passionate (and can complain a lot) about.