This is so sad, but My Friend stopped publishing in June of '07. It was a wonderful magazine and I would recommend finding back issues if possible. My kids ages 11, 9, and 5 (at the time)used to fight over it when it came in the mail! It was kind of like a Catholic Highlights.
The only publication I know of now aimed at children is “Magnifikid!”. It is published by the folks at Magnificat and my children love it too. It is appropriate for a wide range of ages, just like My Friend was.
However, it is more of a liturgical catechesis tool–it is basically a weekly missal for children. It provides brief commentary on the Sunday and holy day readings, and spotlights on the various parts of the mass, and usually a little feature article on a saint wholse feast might be that week, or a lighthearted quiz on a virtue addressed in the readings (i.e., How Humble Are You?) It is very colorful and inspires a sense of wonder and respect toward the Mass and living our faith through the week.
Hope that helps!