The co-author of "Cheaper by the Dozen" and "Belles on Their Toes," Ernestine Gilbreth Carey, was the third of twelve children born to Frank and Lillian Gilbreth.
A famous bearer is American blues/jazz singer Ernestine Anderson (born November 11, 1928). Referred to as "the best-kept jazz secret in the land" by TIME magazine in 1959, she's noted for a number of award-winning recording over a five-decade career, including "The Toast of the Nation's Critics", "Never Make Your Move Too Soon", and "Blues, Dues & Love News", amongst many others.
I've always loved this name. There's just something sweet, charming, soft, and old-fashioned about it. I would not hesitate at using it on a child of mine, as either a forename or a middle name.