The Play & Freeze is a plastic ball with a ball in it. You pack the outer ball with rock salt and ice; you fill the inner ball with ice cream ingredients; you roll the ball around for ten minutes or so (gently but firmly, as the warranty doesn't cover breakage from dropping or kicking) and voila, you have ice cream. Okay, so it's just a twist (so to speak) on the old-school ice cream churn, but it's probably easier to convince your kids to use it.
powerOne reviewer complained that it only makes a pint, but on the other hand, if you have to make the ice cream and then fool around for ten more minutes mixing up another batch, at least you're burning off some calories and perhaps making it more likely you'll just eat what you've got.
Available from Rosker in Gosport, Hampshire, (although unfortunately not online). Should be around £20.
They've recently created the quart size. It's very simple, and we've made three pints of ice cream/sorbet in two nights. Available in the US at REI and L.L. Bean.
Is it better/easier/more convenient than a hand-crank ice cream maker?