Im not sure if this is a pretty standard method, but I thought i would share anyway.
We recently redecorated our living room, and my wife wanted LED mood lighting in the new furniture.
The TV cabinet came with a 5v led strip running through USB, so i connected it to the TV, which had the bonus of turning the LEDs off when the TV was off.
The problem came when I added more lights to the radiator cover and a small table. I liked the lights being controlled by the TV, but it only has 1 usb socket.
So i got an “Arduino Relay Module” :
Wired the signal and V+ to the USB positive, and V- to negative. The relay then switched when the TV was powered.
I then got a powered USB hub, and ran the PSU through the relay. I was then able to connect as many USB LED strips into the hub as i had sockets.
Works well, and is quiet an elegant solution i thought.