I had heard of other widgets doing it, but 'm surprised Extended Controls did it considering how popular it seems to be. And yea, there should definitely be a warning...
I *just* got the phone working again. Odin restored System, still black. Reflashed the kernel, still black. Reflashed the recovery, still black. Did all sorts of cache clears, battery pulls, more cache clears, nothing, screen still black. I couldn't use Clockwork recovery because my SD card is shot. I figured I'd have to get Verizon to replace it, but just for the hell of it, I tried flashing Clockwork recovery (even though I can't actually use it), restarted and surprisingly, it worked. Go figure.