Algodoo

As the title says.
Real world uses are for example :
Small engine starter clutch (handstarting a lawnmower), pedal clutch on a bicycle, I think they even make ratches with it (but the typical click click sound is from another type of clutch).
No scripts used, just geometry.

left - spin in free direction
right - spin in blocked direction

the blocking mechanism works like this :
when the wheel turns into the blocked direction, the bearing balls get stuck between inner and outer wheel, the harder you try to turn, the harder they get pressed in. Like a door stop. The other direction is free (and in this case with extra ball bearings for even better spinning). Small springs press the big ball bearings just close enough to the outside, that the balls get stuck immedeatly when turning the wrong way and there is no play in it.