well.. i NEED
phone
text messaging
contacts
calendar
email - so i can check my jobs while out
iPodness - my phone holds more than my iPod so I dont take the iPod out anymore
Photo album display - I often show people my photos on the phone, showing them on a normal phone is TERRIBLE. My mate has a habbit of chucking me her sony K whatever and telling me to flick though the hotos, the screen is SO small its pointless
googlemap - been handy on MANY occasions as my satnav is pretty old
HANDY features are
twitter skype and wordpress clients, ebay and papal, airshare, apple remote and facebook (sometimes)
its different if youre infront of a computer all day and have access to everything, but if youre out and about, once you get used to haveing everything there, and then if someone suggests you dont need it, you think, but why would i give it up?
its a bit like someone saying, what do you need in a car, who needs aircon, a radio/cd player, leather seats, airbags, abs, etc.... yeah, it'll be a more expensive car, and more likely to go wrong, but we want it still....
unless you buy a BMW, in which i believe all the above, are still options....