Here is a fun problem that came up on chesstempo this morning.
White has just captured a N with f:e5. There seemed to be 2 candidate moves to check, Qc1+ and Bc1+. Qc1+ seems to be a deadend after Kd3, so that leaves checking the line for Bc1+. The solution is 11-ply deep, but it is all forced so it is fairly easy to calculate and keep straight in your head. Solution after the break.
1..Bc1+ 2.Kc3 Qd4+ 3.Kb3 Qb2+ 4.Kc4 b5+ 5.a:b5 a:b5+ 6.Kd3 Qd4# In the final position the way the White King is situated with pieces blocking the retreating diagonals is a common mating pattern for the Queen.