Ever since I got my Google Nexus One, I been using my mobile a lot and no, I don’t make many phone calls. Recently I saw someone else using an Android phone, but using the touchscreen keyboard to find and type one letter at a time. There are various softwares available that will help you type faster but the one that I use is SlideIT from Dasur.
It is available for Android, iPhone, Winodows Mobile and Symbian. I think that should cover almost everyone I know.
If you are still not sure whether it is for you, check this video. (I can type faster than that guy)
Some of the other options available are:
Swype (Still in Beta)
ShapeWriter etc etc.
You can download the demo of SlideIT from Android Market or purchase it from Dasur