It's not that big on this side of the world, but Trevor Baylis's wind-up radio had a huge impact in poor parts of the world, where batteries or electricity were sometimes hard to come by. Sadly as the linked article explains, the prolific inventor (including of a wind-up mobile phone charger and shoes that would charge a device while you walked) died broke because of patent laws that didn't protect him.

Inventor of the wind-up radio Trevor Baylis dies 'in poverty' aged 80