Fictional doodad: The PADD from Star Trek. Its initials stand for Personal Access Display Device, and the Federation gadget allowed users to remotely access databases, enter logs and play back audiovisual content with a touchscreen and a minimum of buttons. Other races in the Star Trek universe had similar equivalents. You mostly see 'em in Next Generation, but there were precursors in the electronic clipboards and data slates of the original Trek series.
Real-world counterpart: The iPad. I mean, look at the thing! Look at the name of the thing! You think Steve Jobs watched a little bit of Trek in his day?
The function we’re still waiting for: Subspace communications. 3G iPads are great and all, but what happens when you leave Earth altogether? We say, it's high time that Apple figures out how they're going to support Starfleet. Putting a communication satellite in orbit sounds like a good start.