ipaq sleeves as an example for hardware extensions

[kenneth marken]

http://www.mobiletechreview.com/tips/ipaq_sleeves.htm

specifically check out the "compaq pc card expansion sleeve plus".

its a pc card (pcmcia iirc) addon that would allow the user to add 
anything, including wifi cards and similar.

sure it will add bulk to the phone, but the flexibility that sleeve 
based solutions allow is incredible.

further down the list there is a sleeve that adds a digital camera.