As a player: sr.league championship game, I broke up a no-hitter with a leadoff single to RF in the top of the last inning down 6-0. At the time, it didn't seem like a big deal but we went on to score 6 runs in the inning to tie the game and went on to win the championship in extra innings. I scored 2 of those runs (walked next AB))and got the game ball even though our #3 hitter hit 2 hrs that game.
As a parent: son went 4-5 including a 2-run triple and 3-rbi, 3 SB and 4 runs scored in an upset win in the opening round of the county playoff tournament. They got got as far as the 3rd round and were 3 outs from making the quarterfinals before getting eliminated in an extra inning game against the #3 ranked team in the area in a 2-1 10 inning game which was one of the best HS games I've ever seen played. Before eventually losing in 10, he made 2 defensive gems which at the time kept the lead and the game tied.
The other was in the Babe Ruth district semi finals, son went 5-5, 9 rbi including a grand slam to get to the district finals.