The iTwinge is a mini physical keyboard that you use on your iPhone. It is designed to be an alternative to using the iPhone's built in keyboard.
The iTwinge is designed for those who are heavy texters or emailers and works as a muscle memory builder. The site who sell the iTwinge do say it can take up to 4 hours to get used to how it works and get comfortable with the keyboard.
The iTwinge costs $29.99 and is shipping now from the link above. They do ship out of the US to Canada as well as internationally too.
It is compatible with both the iPhone 3G and the 3G S.