A chastity device (male or female model) that only unlocks each day after you've written a set number of words. That would up my word count!

Of course, how useful a motivational tool this would be is entirely dependent on your sex drive.

Also, I normally keep my love of pony and my love of bondage separate, but hot damn KRD draws some good shit. I totally didn't discover this after a search for "chastity" on derpibooru. <---LIES!