We've all used the very useful 'predictive text' (T9 text entry system) feature on our mobiles when either emailing or texting. It's the system that accurately correlates number patterns to spelled words.
Well the creators of that system have developed Swype. Swype is a system where users can type blindingly fast on a touchscreen by tracing their finger or stylus over the letters without lifting up. The technology will then connect the letters to form words.
Here's a CNET demo video:
http://www.vimeo.com/1704716
Also here's an old demo video of Android app WritingPad that uses the same interface.