I know LLDP is already a feature request.
That would help. (assuming you know where your wires go)
Another thing/option/method would be to check the mac-address tables in your switches to see where the mac address for each AP is. (switch and port)
Getting management access could be tough if you're a contractor and/or have to deal w/ multiple brands of switches, etc.
There are a number of "network discovery" tools out there that should let you locate MAC addresses via SNMP.
So far, this only helps if you know where the wire is going.
If you've got managed PoE switches, you can then shut down ports where the APs are connected to see which AP turns off.
(essentially unplugging them, like you suggested)
If you're lucky, you can do this without running back to the wiring center.
Having an AP "ID" light would be a lot easier.
This feature is not about knowing where your wires go. I don't want to look for MACs in switches as it is pointless and many times you even don't have access to your switches nor do you know where your wires go.
If you power cycle APs it takes alot of time and you keep disconnecting clients, which usually is a problem.