Take some strong neodymium magnets and place them onto a nonmagnetic but conducting material (for example aluminium). Then tilt the material and let the magnets slide down.
You will notice that the magnets slide down slower than expected. This is due to the eddy currents which are induced in the conductor by the moving magnetic field of the magnets. The currents themselves generate a magnetic field with opposite polarity. The two fields attract each other therefore slowing the magnets down.
This a nice demonstration of Lenz’s Law where the generated field counteracts its generation.
Another cool demonstration of the effect can be found here.