A short game I ran across on chessgames.com, with a really genius ending. White threatens mate with 21. Nf5+ Kg8 22. Nh6#.

wherever blacks queen goes, he'll lose it after N on D4 goes to E6+ or wherever because of the hidden bishop

No, he can save his queen, but at the cost of his king. For example:

20. ... Qc5

21. Nf5 Kg8

22. Nh6#

To save his king, interposing with the knight seems like it would delay mate the longest.

great game! great sac!

note that if white declines then n-f6+ will follow or rxg6 if the f pawn is moved to prevent n-f6

 

(a 15 min game I played last night).  I had hung two pawns early in the game so the sacrifice was the only way I was trying to break through with either the capture of the e f or g pawns but my opponent protected against the e and f pawn sacs nicely.  Fortunately for me she missed the h pawn.