A tastefully done Tablet PC convertible (Read: Standard laptop that can convert into a tablet.) I think Apple could make a real winner in that arena. If nothing else the graphics art professionals would drool over having an Apple laptop that they can work in Photoshop right on the screen.
And then there are people like me that do better in meetings with notepads the going clickity, clickity, clickity on a keyboard. Finally I got to use a tablet for a month at work. It was damn hard to give up. Not because of MSs piss poor attempt at shoe-horning Windows into a tablet roll but from a personalization standpoint. I really got tied to that computer. There is something about interacting with your computer with a pen that seems much more. . .oh I dont know. Does the term personal make any sense? IMHO the experience made me feel like I was more closely tied to the computing experience and that was with the Windows interface. I know Apple could blow the doors off of what MS is offering.
Beyond that I want to see a iPhone type device. Plug the base station into the USB/Firewire port on your computer and plug your analog line into the modem on your computer. The cordless phone could then do IM voice chat, VoIP calls, and standard telephone calls.
The device itself integrates with your computer with voice to text software and always logs your calls with Spotlight being able to access your logs. (with the ability to encrypt the files of course.) The phone would have a color LCD displaying the type of call...iChat logo for IMing, telephone poll for standard phone line chats, and a globe for VoIP calls. Also allow easy handoffs from computer chats onto the phone itself by pressing a button on the base station.