I have a servo motor (tower pro sg90 analog) that I am powering with a 9v battery. I want to attach the smallest switch possible somewhere between the battery and the servo to be able to manually turn the power on and off (or potentially interrupt power with an attached gyro or accelerometer). I know I could buy a battery holder with a switch, but is there another electronics component I could buy to wire in somehow, without the holder? I have no background in EE, so I don't know the appropriate search terms to find this.
A search for micro-switch+slide+toggle will give you plenty of ideas.
Figure 1. A selection of micro-switches.
Just pick one that is rated for your motor current.