Yesterday I came across a very cool post on Scott Westerfeld's blog, which was his 27th tip for NANOWRIMO. I was already familiar with word clouds, but rather stupidly it had never occurred to me to use one to check for overused words in my writing.
Recently I've been using the`Find' function in Word to replace overused words in my novel, but that relies on me already being aware of the trouble word or phrase. I've found I overuse some unexpected words: scan, flick, and attention, to name a few. But a word cloud will tell you which are your most frequently-used words at a glance. Character names are to be expected; others may surprise you.
Read Scott's original post for his excellent description of how to best use word clouds for this purpose.
The other reason to love word clouds is that they sometimes highlight subconscious ideas or obsessions that you didn't even know were in your writing. Today I dug up a forgotten short story for publication, and while I was at it, plugged it into Wordle, and found my word cloud was chock-full of every single body part I could name. Make of that what you will.