How will the I-phone add to technology

I am awaiting my new I-Phone 3GS handset and is looking forward to the benefits that it will holding in for me as a normal Joe Soap.
I have seen some of the applications that are available like sending a 15 second sample of a song to a web service. The web service will recognize the song for you and search online catalogues to suggest an online store for purchasing it online and downloading the song to your I-Tunes.
This is amazing to think that all this advances have been made in the last 15 years since mobile devices have taken off in a big way.
Then there is things like cloud computing that will be holding in some value to roaming people accessing information from anywhere on the globe.
Do you know of any useful applications that is available on mobile devices ?