I would totally use it to keep tabs. Like flu said – you’re a parent.
I’ve been telling my kids for years that when they get facebook they MUST friend me… or lose access to their computers. But they’re still minors.
Fortunately, they haven’t started on Facebook yet… so I’ve been able to avoid creating an account myself. I’m hoping Facebook goes out of favor soon – so I can die without every having had a facebook account.