I use my iPhone for probably 8 hours most days, but I probably make less than a dozen calls a year (and receive not many more).

My iPhone is:

- my podcast player (accounts for most of my daily usage timewise)
- my primary camera
- my primary rss reader
- my primary twitter checker
- my primary email reader
- my mobile music player with all the music I own
- my mobile webbrowser
- my map, compass and gps (and not just Apple/Googles maps either, I have detailed maps for hill walking etc)
- my weather forecasting station
- my calculator
- my train time table
- my TomTom
- my calendar (which syncs with my wife's calendar)
- my address book (which syncs with my wife's address book)
- my alarm clock
- my pedometer
- my remote for my Squeezeboxes
- my notebook (which syncs with my wife's notebooks)
- my mobile scanner (for receipts and the like)
- my video camera
- my photo and video editor
- my shopping list (which syncs with my wife's shopping list)
- my bookshelf, when I haven't got my Kindle
- my password vault (1Password, which syncs to all my devices)
- my bank account management

I'll stop now But that is just the stuff that I use it for day in day out, there are plenty of other things I use it for less frequently.