#SmileBASIC, <s>36</s> 23 bytes
    XON MIC
    WAIT 30XOFF MIC
Blinks the microphone status light.
(video coming soon)

##21 bytes:
    ACLS
    WAIT 30XSCREEN 1
This blinks the 3D indicator light, but I'm not sure if it counts as being "physically located on your keyboard"