Interestinng question! I certainly think three of the songs mentioned so far - Surfin Wild, Can't Wait to Love You, Whole Lotta Loving - could have been been successful singles. Surfin Wild could have redefined popular conceptions of surf music - a great raw, garage number.
I'd also add:
Waimea Bay (great production)
Soul City (groundbreaking track - at first it feels a bit like a filler, but as it goes on you realise its absolutely revolutionary dance track)
The Battle of Strawberry Fields (mentioned it on another thread - just love that song!)