said by Mike Wolf:Don't think I've ever seen any options regarding that light except for the white and amber for the SecureEasySetup function. Would be cool for it to do other things, but I can't think of anything except for perhaps a notification if its overheating or overwhelmed?
default ddwrt uses the light to indicate active wan connection. It could be used to show a specific wireless client, or maybe low memory, or too many tcp connections or just randomly flashing hypnotic device..
GPIO pins are just that. They can be toggled by software at any time.