i've always thought this would be useful for reading books using an iPod nano screen or cellphone etc. i'm sure that if your commute was long enough, you'd find a pleasant rather than arduous speed for reading after a couple hours practice. The earliest reference i can think of for this idea was a Heinlein novel where he basically described web/hypertext (not sure where he picked it up, he was pretty upfront about only needing to be 6 months ahead of the pack to appear to be a predictive genius! ;-)