In Chapter 34 of Fab Four FAQ: Everything Left to Know About the Beatles... and More!, there is a list of 10 odd covers of Beatles songs. It's a pretty star-studded list—Lena Horne, Mae West, and Bing Crosby are all on it.
When the Beatles appeared on The Ed Sullivan Show, every label that wasn't carrying Beatles records took a huge hit in sales. In desperation—today's RIAA willy-nilly litigation party is not the first time the record industry has been driven by desperation—many record labels persuaded their old-school failing artists to try and contemporize by covering Beatles songs.
This strategy revived exactly zero careers, which is probably why I'd never heard of any of the recordings. West's cover of "Day Tripper" is said to "have growled rather uncomfortably through the Fab's guitar-laden raveup." Record labels never seem to understand that a record won't sell if it's unlistenable, no matter the writing credit on the track. "Give Peace a Chance," by Mitch Miller and the Gang (an old-timey troop featuring the president of Columbia Records), also tried to capitalize on John Lennon's genius, but the authors say that the actual track is "out there." I think they are being polite. It didn't sell, either.
Another of these covers grabbed my interest for reasons having nothing to do with industry malaise. In 1973, John Lennon separated from Yoko Ono and lived in California, where he was drinking a lot. He partied with Harry Nilsson, Alice Cooper, and Anne Murray, the Canadian adult-contemporary singer. There are rumors that Murray and Lennon were having an affair, which adds subtext to her 1980 cover of "I'm Happy Just to Dance with You." Even if the song has the worst polka bridge ever committed to wax, the intrigue persists.
I've only read this one chapter so far. But any book that can teach you this much about something you already know a lot about is a very good book.