I use a sheevaplug with a usb cd-rom drive to close the air hatch on my wood burning central heating system. Of course it also has some fishing line and duct tape. The idea is that i can close the hatch with a timer or remotely at will. I've built a website for this purpose. I have two raspberry pis working as cameras for the system. If I leave the hatch open the air getting through the system will cool down the system much faster. I just eject the empty drive and the fishing line gets "longer" and closes the hatch.