Minimize FSX...

[bowler_man]

Is there a way to be in free flight, then put it on pause or slew mode, then minimize FSX, and the bring it back up later and be back where you were?

[LowFlight]

Yep, you can do exactly that if you are using FS in window mode. Hit Alt + Enter to toggle between window and non window mode.

[Daube]

I'm not 100% sure anymore, but I think that you can also just hit Pause, then the Windows key to bring the Start Menu...

[Hansie]

If, during flying you switch to another program ()or bring up the windows startmenu, FSX will pause automatically. Also when an external program pops to the front, FSX automatically pauses. After you've done your non-FSX stuff, you indeed can go back to the point were FSX paused.