I can relate. Sat behind a cranky 3 yr old on the way back from Mephis Sunday night. Temper tantrums, kicking my seat, crying, yelling - parents threatening to beat the crap out of him, but powerless to do so on a crowded aircraft. Oh, it was memoriable.
Nothing can ruin a flight like a kid out of control. If they want to clamp down on something...get some duct tape for the screaming kid!