Teaching is a major one. Social workers (family related work), counselors (college/career), doctors (pediatricians, child psychiatry), all have significant sub-disciplines that deal with children. Even family-related law practice (such as divorce lawyers) will involve some level of making decisions on behalf of, and interacting with, children.
One of the questions you'll have to ask yourself is in what context do you want to interact with children -- do you want to see many, occasionally, or interact with a few dozen on a regular basis? That will help you think about whether you want to work in a school/extracurricular environment like the YMCA, as opposed to in a professional office.
I think it also depends what ages of kids you want to work with. If you are interested in young children, you could become an early childhood educator and caregiver. You can run after school programs for kids in elementary school or rec centers. If you want to help children with special needs, you could look into early intervention services, speech therapy, or occupational therapy. Another great option is being a children's librarian at a public library or a school librarian.
Jobs for People Who Want To Work With Children : Teacher, Day care owner, Pediatric nutritionist, Child psychologist , Coach and Pediatric registered nurse.