Make me a better speeller
I (like most) frequently misspell the same words. I try to take note each time Gmail or MS Word dings me, but I'm still slow to learn.
Wouldn't it be great if Gmail or MS Word ran background analytics on my spelling errors? It could produce a monthly report of the top 5 misspelled words, so that I could work on fixing them in the next few weeks. Maybe even chart my improvement on some words and highlight where I'm just not cutting it.