Well an I-phone or I-Pod touch. Basically, have every next gen Mac book come with an I-Phone for a touch, allowing for a customized readout and keys on the phone for use with the laptop.

Imagine letting phone calls come in through the Mac as a speaker phone, and naturally allowed tethering for the Mac when the phone is plugged in for universal internet access.

Having a second small display for use with programs that are interactive, much like a Nitendo DS might be used. Even have the possibility of dragging custom Apps from the main Mac screen onto the I phone like stock and new feeds, aim conversations, etc only while docked...

With add on touch screen pads that are program customizable coming out now days, having one that would seamlessly synchronize with the Mac world would be perfect. And for use of the laptop without the I phone in the Mac, have a generic one like now be hot swappable and placed in for basic usage as now.