Most of the time I only need a small candy bar smartphone that is extemely convenient to carry around and which is fine for calling, occasional e-mail reading and some limited Web browsing. However, sometimes I need to type an answer to an e-mail. But I don't have to do it very often so I don't really want to be carrying around a PDA-style smartphone with a keyboard or even bigger device. And sometimes I definitely want a big high resolution screen so I can browse Web more comfortably. And 3.5" PDA screen is not enough anyway.
How do we solve this in the world of ordinary computers? We carry around 12" light laptop and connect it to a big screen and an external keyboard when necessary. So what I want is 5" or 7" screen with dock where I can insert my small smartphone and be able to browse Web and read documents on 7" 800x600 screen instead of 160x120. Same mobile plan, same device, same applications, same favorites, same contacts. No need to decide if you need small device, large PDA or in-between compromise.