pidgin-blinklight is a plugin for Pidgin that will blink your laptop's leds when you get new messages, so you can notice them even if the conversation window is not up front and you don't have or don't see the window list.
To use this with an Thinkpad's ThinkLight, you need to have the ibm-acpi kernel module loaded.
To use this with an ASUS laptop, you need to have the asus_acpi kernel module loaded.
My Thinkpad laptop has a small light in the frame, originally ment to enlighten the keyboard in dark environments.
I use it to indicate new pidginext. messages. New versions are uploaded directly to the debian archive, users of other distributions can get them there.