[wallunit]

Awesome, I'm looking forward to see whether it is working on your Acer laptop.

You can use anything that is exposed by the Linux kernel under /sys/class/leds/*. This includes the keyboard backlight of ThinkPads. As for other vendors, it depends on whether the keyboard backlight (or any other LED) can be controlled in software, and if so whether it is supported by any kernel driver.

[Johnnynator]

:( literally every light can't be toggled, except the usual stuff like numlock or capslock.