Being on the run, and trying to get something else done is absolutely the wrong situtation for browsing or navigating. On a mobile device you want just a few choices presented at any given time. Mostly, you want your work handed to you in a well-defined order -- much like an MS Windows wizard. You want to be led through the task with just a few choices presented in context.
The paradigm for the typical web site is exemplified by Yahoo or Amazon. Just look at how many links are on those pages! These sites require intensive browsing and navigating. This is not usually a problem because fonts, graphics, and layout are used to visually organize the links, allowing you to quickly search the page with your eyes to find the link you want. This approach only works, however, when you have a big screen. Even with the smart algorithms in portable browsers like Opera typical web pages have way too many links to make browsing convenient and easy.
A portable application should “disappear” when it is in use. That is, using the interface should not require any understanding or thinking or conscious work. Navigation and manipulation of the interface should not be something the user thinks about consciously. This is what Martin Heidegger calls “ready to hand”.
Russell Beattie has a nice discussion of mobile browsers, with a similar point. He believes that we will eventually create a whole separate web designed for small devices and small screen browsers.
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