Seriously, though, the kind of person who's going to want to simulate the flight he's on would encounter a number of frustrations in attaining the kind of accuracy such a person would want. For instance, you wouldn't be able to simulate pushback, taxiing, takeoff, and the first few minutes of flight because your computer would have to be off. Then even if you started the sim up in mid-flight, it'd be hard to estimate exactly where in the projected flight path to "join in," so you'd know you were always off by a significant margin. Also, while ATC is simulated, the actual situation with other aircraft will likely lead to a discrepancy between the simulated ATC and the instructions actually given to the pilot, so while you're lining the simulated flight up for approach on runway 11, your actual flight is entering a holding pattern for runway 4. Finally, of course, you'd have to put the computer away for the actual landing.

To top it off, they just don't make travel-size joysticks, much less yoke-and-pedal controllers.

I suppose I've thought about this more than is really healthy...