My Sony VAIO PCG-838 came with a little widget that plugs into the headphone jack and into the small odd-looking data port next to it. I can plug in headphones into the widget.
It has a volume dial, which is just a pot and obviously works without software help, and it also has three buttons (labeled appropriately for controlling a CD player). Does anyone know how to access this port? I'd love to make those buttons usable in Linux, but I don't know where to begin.