I remember running a small Windows app that would sit in the background and pipe sound of various frequencies through your speakers depending on system state. I think I had mine set up to rumble at 30 or 40Hz at 50% CPU and slowly increase the volume as it got past that point.
One night after I turned the volume up for a particularly quiet movie I fell asleep and let folding@home go. I woke up a couple minutes later with my subwoofer rattling the entire room and my roommates knocking on my door to make sure the place wasn't falling apart.
