1) Special characters. A lot of them are 2 clicks away -- I would prefer to have a bigger keyboard when I click the "1,2,3" (i.e. an additional row). As clicking the "#+=" afterwards only changes one row.

2) I'd love to try a swipe/gesture interface (like Android).

3) A keyboard optimized for one-handed typing. This is a bigger project but would be great. The ones I've seen so far aren't very good and obviously don't actually replace the default keyboard.