Taken from one of my recent correspondence games - white is down a pawn, but very obviously winning. The game concluded with:
24. Qh2 f6
25. Ne6!! Resigns since black must lose at least a piece to avoid mate.
However, there is a much simpler way to finish the game. I had calculated it out before, but didn't write it down anywhere, so when it came time to make my move days later, I had forgotten all about it!
24. Rh8+!! Bxh8 (If ...Kxh8 then 25. Qh2+ and mate via Qh7#)
25. Ne6+! Bg7 (If ...Kh7 we have the same Qh2+ mating idea)
26. Rxg7+ Kh8
27. Qh2+ Qh4