I would love to see something about the size of an 8.5" by 11" notebook, with a high definition led screen, that takes up most of the top surface of the device, with wifi, standard SD card slot, a usb slot, speaker, microphone, headphone jack and a built in web cam.
The devise could run a couple of super efficient parallel processors and run a somewhat better finished version of Android (mainly something that allows you to navigate running processes and kill them without having to download an app for this and which runs a more flexible desktop (like Dxtop or sweeterhome) as the standard desktop. The device should have a long battery life under heavy use, be very light and be tough. Most importantly the device should be priced to compete directly with todays netbooks (think $300 range), but offer better performance.
IMHO such a device would be something that many folks could keep in their bags as a primary traveling computer, and which students could keep on themselves as their primary machine for most of their classwork.
Now that is a device I would be interested in buying and which i think would have uses far beyond school and book reading. I can easily imagin a 3/4 g enabled version being used by surveyors or engineers who would be able to carry detailed schematics and plans around with them and actually be able to see and use them in conjunction with features such as GPS location. I can easily see military folks using such devices in the field.
Apple's max-Ipad is nice, but at this point it is little more than an oversized Ipod Touch (and not much more), and it's price pretty much guarantees that it will remain little more than a curiosity. It's cool that they were first to market, but I just don't think that this one time they nailed the device or that a second generation of the device will be quick enough to market to top what the competition might have in mind.
BTW, I also think that items like that dell shown above are little more than slightly oversized smartphones and not true tablets. I don't think they will be particularly popular either, as they are just too small to effectively differentiate them from what good smartphones already do.