Several people commented that it would be good to have a fast thumb-typing for SmartPhones that can work with a single hand, in case you don’t have two hands free.
The following variant seems to do the trick: The 14 fast characters are the same, but the other characters are “typed” not by chording, but rather by sliding off the original virtual key in one of the principal four directions.
Click on the image below to link to a java applet that shows the idea:
Using this approach, you can pick up a lot of extra speed by using both thumbs, but everything still works (albeit more slowly) with a single thumb.
I’m pretty sure one could prototype this for the phone with App Inventor. It would probably have to be implemented with an image map on a Canvas. Given the image map you could use Touched and Dragged events for the key presses. App Inventor doesn’t have the concept of image maps directly, but it can be coded. The TextToSpeech component could be used to speak the recognized character as an option. Maybe I’ll try to make the app if I have a chance tonight.