The idea for TypeThis started out as a bet between two friends to see who can text the fastest on their cell phones. TypeThis founder, Hyung Lee recalls, “A few months back, a friend said that I was taking too long to respond to his text messages and blamed it on my slow typing, which led to a debate about who actually was the faster texter.” That was the moment when Hyung realized that there should be a game for that.
iPhone and iPad apps tagged "typing tool."
Big Keyboard Email: Improve Your Typing Skills with a Wide Keyboard
An oft-ranted complaint about the iPhone is that users can't access the horizontal keyboard when typing emails. Several developers have tackled the issue including Big Keyboard Email.