VHDL/Verilog as well, but that's completely obvious.

I've been using state machines for Javascript UI elements.. really simplifies things.

Gesture detection/interaction here. All state machines all the time.

Life cycle management, process synchronization, lockfree data structure, user-space networking... I can't remember the last time I didn't use a state machine.

As someone who troubleshot networking issues for years, god bless you.