I use it as a drink coaster.
I also used it to pound a nail into the wall to hang a picture.
I played ultimate frisbee with it (I won too!)
Yesterday my chair was a little uneven so I slipped the iphone underneath and it did the trick
I was having trouble deciding on what color to paint a desk - yellow, eggshell or whitish/blue - so I used the screen to determine which color I liked best
....
In all seriousness - my iPhone replaced my blackberry which was starting to have massive failure do to age/use. It also replaced my ipod touch at the gym/commuting and in the future - travelling.
So for me - it's an ipod, screen to watch/catch up on news/sitcoms, email/txt machine, phone, and other apps like google maps, urban spoon, etc.
I have light and heavy phone usage days - it all depends.