Probably already mentioned but the 1980 Semi Final replay against West Ham was a tough one to take.
Watched it on Sportsnight without knowing the score. Didn't understand how we could get taken apart by a second division side (Devonshire had a blinder), then the winning goal somehow crawling into the bottom corner at a funereal pace. In those days the cup was a bigger deal...
Allardyce becoming our manager is right up there too.
1977 Semi Final, Bryan Hamilton being denied the winner by Clive Thomas - so proud of the boys that day.