I have this port on my laptop and I have no idea what is it used for. It's not even listen in the laptop technical specifications. The laptop is a HP Pavillion dv5-1101en.
Here is a larger image showing all the ports on the laptop:
Left to right:
- D-sub 15 pin (AKA VGA)
- Unknown port
- IEEE 1394 (AKA FireWire)