Job/service idea - need input

As I look for a good job, I am trying to be creative and come up with start my own business ideas.

I have a neighbor family who has 2 working parents and 2 kids in school. The other day one parent came home from work to care for a kid who had hurt his foot. I told them I am home during the day and offered to be called if they ever needed help like that, again.

Having watched "concierge doctors" on both Royal Pains and Rush, I wonder if there isn't an opportunity to help parents who get called about sick kids at school. Could I be an on demand nanny/nurse who could fill in and take care of kids until their parents got home after work? Do you think I could send out mailers and business cards saying that:

1) When your kid becomes sick at school...call me to fill in until you get home from work.

Is this something you see as possible, or not?