Oh, man, I'm so sorry about your friend's daughter. Bite Blocker claims to repel ticks, but I don't know if it's been tested. I usually only see a couple-three ticks a week in season anyway, so I can't really speak from experience. But they're saying deer ticks are becoming more prevalent in my area.

It's easy enough to check myself for ticks before and in the shower every day - I keep reading that a tick has to be embedded for at least 24 hours to transmit Lyme (the CDC actually says 36-48 hours) - but I don't know what I'd do if I had a child. Toxic chemicals, invasive inspections or risk of deadly disease.