Okay, this isn't so much a tool as a prompt help. Getting stuck and don't know where to go? Then challenge yourself to use the "word of the day" -- and get a giggle from reading it via "Word of the Duh" blog!
I've challenged myself to find a way to use the daily word somewhere, somehow in my WIP. It helps my brain work in a different way, and sometimes encourages me to brainstorm new scenes and new possiblities.