What are some of the practical applications of a Flywheel?

What are some of the practical applications of a Flywheel?

Recently, flywheels have become the subject of extensive research as power storage devices for uses in vehicles; see flywheel energy storage. Flywheel drive is common in low-cost toys.

A momentum wheel is a type of flywheel useful in satellite pointing operations, in which the flywheels are used to point the satellite’s instruments in the correct directions without the use of thrusters.