Billy Joel "My Life"

Listen closely to Billy Joel's little ditty "My Life" and you'll hear the vocals of Peter Cetera and Donnie Dacus singing "Keep it to yourself it's my life". Both were members of Chicago in 1978 when "My Life" went to #2 on the Adult Contemporary Chart.

Samantha Sang "Emotion"

Her first name might not be Samantha (it's Cheryl), but her last name is definitely Sang. After beginning her career as Cheryl Gray, the Australian changed her name to Samantha Sang signing on with Barry Gibb's manager. Gibb was such a fan of hers that he even sang backup vocals on "Emotion". The tune is Sang's biggest hit to-date. Destiny's Child covered the song in 2001--leading some Adult Contemporary radio stations to spin the tune again.

Doobie Brothers "What A Fool Believes"

BELIEVE IT OR NOT?

Michael Jackson once boasted to his pal Elizabeth Taylor that he provided backing vocals for the Doobie Brother's Minute By Minute album--specifically for the title track as well as the album's biggest hit: "What A Fool Believes". Members of the Doobie Brothers dispute this story.

Nicolette Larson - "Let Me Go, Love"

The buttery smooth voice of Michael McDonald supports Nicolette Larson in the 1979 dentist office favorite, "Let Me Go, Love".  While the song isn't considered a duet, one listen to the tune and you'll agree McDonald does more than just provide backing vocals -- in fact, some have argued that his voice overshadowed hers.