Yes, it's goofy, but
Written? Kitten! really is fun! With this simple word processor you are rewarded for every 100 words (or you can set a higher number)... and your reward is a random picture of a kitten. And it's not just kittens: they recently added a new feature so you can get a puppy or a bunny instead. :-)
Here's the blank screen before I typed 100 words:
And here's the reward:
So, if you are looking for a text box that will reward you for how much you type, this site might work for you! :-)