Nicely done! I really enjoy this concept, and the presentation is simple and elegant. I think I might need an Easy Mode though; the timer is a bit too fast for me, even at the beginning. Or how about, in addition to Time Attack (let's call it), there could be a Strategy mode in which new rows are added based on the number of words you've spelled rather than time taken. That would be a very different style, encouraging players to take their time and spell more complex words.