2002 - After taking the first two games in Detroit against a hall of fame, eventual cup winning Red Wings squad Dan Cloutier lets in a goal from centre ice which changes the entire momentum of the series. Vancouver loses the next 4 games and Cloutier was never the same in the post-season (and his subsequent post-season meltdown was more or less the end of his career).
I'm sure there are others, but that's the one that has stuck with me for the past 7 1/2 years.
Tough to choose the biggest goal, since they haven't won the biggest prize yet.
The MayDay goal certainly ranks up there in franchise history. It emphatically ended a decade-long stretch in which the team hadn't managed to win a single playoff series.
Biggest Goal: Has to be Game 6 of the SCF 30 seconds into the second OT when Marty St Louis scored to send the series back to Tampa for Game 7 and eventual cup win.
Most devastating probably 1994 ECF Vs the NYR double OT
Runner up has to be the 2 in 80 seconds last year vs the canes
Biggest is probably Arnott's cup winner in double OT vs the stars in 2000
Runner up probably Johnny Mac's OT winner vs Pang and the hawks to get the devils into the playoffs for the first time in 88 (only runner up to me because the devils won the cup on Arnott's goal)
1971 Stanley Cup Finals Game 6 Hawks lead the series 3-2...
Blackhawks are dominating the Habs late into the second period 2-0. Not long after Bobby Hull hits the crossbar (which would have essentially sealed the game) Jacques Lemaire scores on a shot from CENTER ICE to make it 2-1 (Esposito was known for not being able to see long distance shots well). Montreal comes back to win the game 4-3, and then takes Game 7 in Chicago. Many have said that goal was the turning point in the series.
I cannot find the article, but I also remember that Bobby Hull said if they had won the Cup that year he probably would not have left Chicago for the WHA.
This happened 10 years before I was born, but as a Hawks fan all my life I have heard this story told more times than I can count.
I was only 2 years-old- but I've always been told that Lanny McDonald's Game 7 OT goal in the 77-78 quarterfinals propelling the Leafs past the favored Islanders was extremely devastating at the time...
As far as actual personal experience goes- I think it would have to be the 2 OT goals in the 1993 Wales Conference Finals against the Canadiens... The Isles played the Habs tougher than the 4-1 game score would indicate... Just ran into a team with even more OT mojo than they had that year...
Meanwhile... we've had some big goals... but nothing can ever touch Bobby Nystrom's OT Cup winner against the Flyers in '80...
Most devastating has to be David Volek in 1993, Game 7 OT. The Pens had one of the best teams in the history of the NHL, and they lost their season on a soft floater in overtime.
Talbot's goals in Game 7 in June were pretty big. I also have to give mention to Lemieux and Jagr's beauties opening up the 1992 Finals at home against the Hawks.