Combo of:

-Surf the web without need for "apps" front or tin client thanks to excellent browser and top notch resistive touch screen...

-Surf the web mobile without adds (Adblock / Noscript /
-Maemo multitask interface (although I expect the competition will copy it at some point in time - Android 4.0 or something)
-Draw and write with stylus, with pressure sensitive input.
-HW Keyb (I expect the competition will copy it at some point in time)
-Integrated Skype and SIP
-Play Wagic
-Practice Linux commands
-Enjoy enhanced "Mugen" Power bat
-FM Radio transmitter
-Debian + Open Office , The Gimp

Loads of really useful applications such as Front View etc that make this N900 a joy to use. (But those may be available on other platforms, I did not check)

a proud iPhone 4 buyer was waiting for the staff to apply his screen protector and witnessed us pay a Macbook via Online banking using the Stylus and Hardware keyboard efficiently without stress, without app on N900.
I saw him wondering how he would do that on his iPhone. I am sure he can, but not to suffer he needs to select a bank that has written an app for his phone , so unbelievable 2007

N900 rules