Check out Caryn Mirriam-Goldberg's essay, "The Invisible Friend of the Page: Writing as a Transformative Practice" at the website for The Spirit of a Woman, which features stories to empower and inspire women, men, all of us! Here's the first paragraph:

When I was a child, I didn’t have any human friends. It wasn’t that I didn’t want friends; I just didn’t understand how to get them. Hard-wired for interior sound from the get-go and growing up in a tumultuous home, I found imaginary friends for each day of the week. Monday was an older sister, reserved and confident. Tuesday had straight blond hair and a penance for dolls. Wednesday and I were thick as thieves, and she understood me best. Thursday was a standoffish brother, Friday a party animal, Saturday a patient and exhausted mother, and Sunday, a distracted father. More at this link!