My mainline for white is the scotch gambit.
The theory is so complicated that I have had people resign in completely equal positions, like this one:
Or something like this, he may have played Be7.
The fact that black resigned in that position says more about the player than the theory...
Nice. I play that line all the time as Black. It's true White can slightly kill the game with somethin like 10.Bg5 Bb4 11.Nxd4 but they will often play very substandard moves such as in the position above 13.Bg5 Bxh2+ or even 13.Qe2 which loses quickly to ...d3! or as per the game above.