new chapter; request feedback.

[seele@obso1337.org]

Looks good, only thing I would work on is the 'know your user' example. 
Of course, I dont have any better suggestions, so maybe its not so bad..
"featuritis" is what pops in to my head, but coming up with a concise
example is a little more difficult.


>
> The 'know your user' part requests an example.  I was thinking about an
> example feature like:
>   Ledger application targeted at bookkeepers comes bundled with a new
>   feature; a simple pop-up calculator.
>   A simple calculator is useless for a bookkeeper; plus most of them will
>   have one on their desk anyway.
>
> Anyone got anything better?