OP gave the two answers that jumped to my mind - Like a Rolling Stone and A Hard Day's Night - but for the artist(s) with the most examples, dig out your Abba collection. I reckon that the first second of the following songs are all immediately identifiable: Summer Night City, Dancing Queen, Take A Chance On Me, Super Trouper, Waterloo. Great pop operates from the first bar ...
By the way, a couple of people have mentioned Metallica's "Enter Sandman", and by my reckoning you only get one note on electric guitar to identify it. For this, and several other suggestions, I think that you'd need 2 or 3 seconds.