3 Acer 22" monitors connected to an EVGA GTX 560 TI superclocked via a Matrox TripleHead2Go digital version.
3 Acer 19" monitors connected to 2 EVGA 9600GT.
And you get this when you take a screen pic:
Of course I had to connect the 2 9600GT cards to a 2nd 300W power supply or else the PC would just turn off. I've reached the point where 800W is just not enough.
BUT, I can ALT-TAB in and out of FSX in windowed or full screen mode without windows crashing.