Fame
Unless the kid you're taking care of is Suri Cruise or Blue Ivy, you probably won't end up in any tabloids for your work. The only people stopping you on the street will be the ones saying, "Sorry, you dropped something," or "Which way is Fulton Street?" or "Is that your child rummaging through the trash can over there?"
Still want to get your name out there? Your best bet is to start up a reality TV show starring yourself. On second thought, spare us. The world has enough Supernannies. Just go do something else.