ForeFlight can be connected to Flight Simulator programs running on desktop/laptop computers, or even full-size simulators.  Depending on the simulator, the connection can either be via WiFi (using the "UDP" protocol) or by a wired connection to the iPad.

Simulators supported by ForeFlight are:

 1.  ELITE

 2.  Infinite Flight

 3.   Microsoft Flight Simulator 2004 and FSX 

 4.   Prepar3D

 5.   RedBird

 6.   X-Plane